I’m having the same problem.

I already tried. It says it’s synced, but still won’t work.

I tried again, and am still having the same problem.

It started working for me again (tough I didn't sync again).

Quote from spamandtuna >>

For anyone still having trouble accessing the book, the issue should be fixed!  Try syncing your entitlements one more time, and please let us know if you're still having any trouble.

It's working now! I can access MM from the D&D Beyond website and mobile app!
Thanks :)

I have no button that allows me to sync my entitlements, under licenses it just says "your entitlements data is in sync"

Fun times :)

Carrion Crawler has a Dex Based Paralysis that requires a Dex save to bypass.

Dex-Saves auto fail if Paralyzed.

Quote from spamandtuna >>

For anyone still having trouble accessing the book, the issue should be fixed!  Try syncing your entitlements one more time, and please let us know if you're still having any trouble.

I finally got access this morning! Though the Licenses page always showed everything already synced before, this morning the sync option was available, and it resolved the issue.

- Your account entitlements are in sync. (If not, there should be a button to sync them.)

My Licenses page says that everything is in sync, I do not have a button that allows me to sync my entitlements.

- You have an active Master Tier subscription. (Hero Tier gets early access on the 11th, and everyone else gets access on release day, the 18th.)

I have a Master tier subscription and I have access to everything else that Master tier entitles me to.

- You have that book listed under Current Product Licenses. (If not, you haven't preordered the book or haven't entered your redemption code.)

My product licenses simply state master tier because I have an educator account

Nimble escape is very different from the prowl ability. I’d like to be able to see the Tiger and Panther statblocks from the PHB I purchased. 

This is what the tiger’s statblock was like prior to the monster manual releasing, and this is what it says on the physical PHB. 

Multiattack. The tiger makes one Pounce attack and uses Prowl.

Pounce. Melee Attack Roll: +5, reach 5 ft. Hit: 6 (1d6 + 3) Slashing damage. If the tiger had Advantage on the attack roll, the target takes an extra 3 (1d6) Slashing damage and, if it is Huge or smaller, has the Prone condition.

Prowl. The tiger moves up to half its Speed without provoking Opportunity Attacks. At the end of this movement, the tiger can take the Hide action.

This is what the Digital Monster Manual, PHB, and free rules says that all tigers have instead now.

Vampires have no text saying that they don't die or go unconscious at 0 hp. As written at 0 hp they just transform into mist and immediately die.

Not sure if I post it here or to a thread about the D&D Beyond app, but the native “Contents” button (the three bullets) in the upper right of the book page has a number of missing entries.

- Essentially almost every (but not all) of the first monsters in a section only show up if you select the Monsters title. E.g., Faerie Dragons don’t show up on this list as a hyperlink, one must click “Monsters F” and then Faerie Dragon is under the section title.

- Other monsters are missing from the list. “Green Hag” for example doesn’t show up there.

They seem like similar issues, that a “break” was not put there nor does the monster title have the right header tag to it.

Quote from WhitestElric >>

Vampires have no text saying that they don't die or go unconscious at 0 hp. As written at 0 hp they just transform into mist and immediately die.

 It says what they do instead of dying. Specific beats general. 

Quote from WhitestElric >>

Why aren't Owlbears reclassified as Beasts so druids can wildshape into them? This seems like an unforced error given the movie.

As people already discussed when the movie came out, that was something they did because it was cool for the movie. The movie didn't operate 1:1 with D&D rules, even though it was largely inspired by them. (See Speak With Dead's use for another example, which was great.)

Quote from HopefulHeart >>

Initiative score for Vampire and Vampire Umbral Lord both seem off; it says  +14 (24) but there is nothing in the description or stat block that explains this high score. I expect that it should be +4 (14)

 

EDIT: it appears to be this high on many Legendary monsters,  something like expertise on initiative?  Is that defined somewhere?

Expertise on Initiative is exactly what it is. See the point on Initiative in the MM 2025 from the Introduction to see where they discuss adding other things, such as Proficiency, to some monsters. Additionally, they'd already hinted at doing this in interviews in the lead-up to the Monster Manual (though I don't have a direct link to that at this time, it would take some sorting through; probably in the Dragons video).

Quote from Maialideth >>

The Cultist Hierophant has AC 16, but with Dex 18 and Mage Armor as per spellcasting trait, it should have AC 17. It also has Breastplate gear, which would match its AC, but then Mage Armor doesn't make sense.

You're right. The AC actually matches a Breastplate with their Dex, as they would only benefit from +2 of their Dex mod.

Quote from Athanar90 >> 

Quote from HopefulHeart >>

Initiative score for Vampire and Vampire Umbral Lord both seem off; it says  +14 (24) but there is nothing in the description or stat block that explains this high score. I expect that it should be +4 (14)

 

EDIT: it appears to be this high on many Legendary monsters,  something like expertise on initiative?  Is that defined somewhere?

Expertise on Initiative is exactly what it is. See the point on Initiative in the MM 2025 from the Introduction to see where they discuss adding other things, such as Proficiency, to some monsters. Additionally, they'd already hinted at doing this in interviews in the lead-up to the Monster Manual (though I don't have a direct link to that at this time, it would take some sorting through; probably in the Dragons video).

 

I would have liked more information, either in the DMG or in the MM, about the design of monsters. Just a mention of "oh yeah, we may or may not have added extra modifiers" is very unsatisfying and raises more questions than it answers.

In the 2014 DMG there were 10 pages about how to create a monster, in the 2024 DMG just barely 1 1/2 page. And in these 1 1/2 pages there is nothing about Legendary creatures and why they maybe have a higher initiative score. I've seen the video. I'm just sad that information like this is not in the books. The videos will be forgotten in a few years (if not months) while the books will still be available online and in hard copy.

Quote from TalosTheStormlord >>

Not sure if I post it here or to a thread about the D&D Beyond app, but the native “Contents” button (the three bullets) in the upper right of the book page has a number of missing entries.

- Essentially almost every (but not all) of the first monsters in a section only show up if you select the Monsters title. E.g., Faerie Dragons don’t show up on this list as a hyperlink, one must click “Monsters F” and then Faerie Dragon is under the section title.

- Other monsters are missing from the list. “Green Hag” for example doesn’t show up there.

They seem like similar issues, that a “break” was not put there nor does the monster title have the right header tag to it.

 
I can confirm this. Tried Android phone and Android tablet and I can replicate this in both.