Don't know if this is known (I tried to look, but couldn't find it). This was the only problem I could find when I added the optional features to my monk.
Quickened Healing
As an action, you can spend 2 ki points to regain (scalevalue+proficiency)#unsigned - No level scale data available hit points.
There are a number of issues with the Ranger Optional Class traits.
At 1st level, Deft Explorer gives Canny. The skill selected here should get double proficiency bonus, so basically expertise. ("Your proficiency bonus is doubled for any ability check you make that uses the chosen skill.") It only gives proficiency at present.
At 6th level, it should give Roving. This is not showing in my list of class features. It has given me a climb speed and swim speed, but it has not increased my walking speed by 5.
If I activate Primal Awareness, it does not display as a class feature. Primeval Awareness, which it replaces, still does. It does add the relevant spells to my spell list though.
Favoured Foe description shows "you can increase that damage by scalevalue - No level scale data available." If you click into it, it shows the correct levels of damage.
Despite having taken Favoured Foe, which is supposed to replace Favoured Enemy, class features is still showing Lvl 6 Favoured Enemy selections
For the monk optional class feature, Dedicated Weapon, will there be a way to set the dedicated weapon on the character sheet? For example, I'd like to set darts as my monk's dedicated weapon, so that the sheet accurately reflects it as a Martial Arts weapon.
The first time on each of your turns that you hit the favored enemy and deal damage to it, including when you mark it, you can increase that damage by scalevalue - No level scale data available.
There is a minor bug with the cleric optional class feature Harness Divine Power in the features & traits section of the character sheet.
You can expend a use of your Channel Divinity to fuel your spells. As a bonus action, you regain one expended spell slot of up to level 2. You can use this feature scalevalue - No level scale data available times. You regain all expended uses when you finish a long rest.
Can't seem to find Mislead as a 5th level spell for my Warlock.
EDIT: Make that any of the 5th level spells, the other are there. I did indeed ensure the Optional Feature check was marked, and cleared my cache.
EDIT EDIT: While all spells of lower than 5th appeared originally, once I added the additional spells checkbox in Optional Features Manager, the 5th level spells showed up.
I made a character with a Tiefling subrace. The ability score change seemed to work fine but I noticed the character sheet is displaying both the standard racial increase and the new variant increase at the same time for 6 overall instead of 3
The first time on each of your turns that you hit the favored enemy and deal damage to it, including when you mark it, you can increase that damage by scalevalue - No level scale data available.
That is all the options i can see, when i choose Mountain Dwarf:

On the home page for that character, do you have the optional rules clicked?
It does not do this automatically.
Additionally, rogue optional features and artificer optional features are not available to select at all.
Don't know if this is known (I tried to look, but couldn't find it). This was the only problem I could find when I added the optional features to my monk.
As an action, you can spend 2 ki points to regain (scalevalue+proficiency)#unsigned - No level scale data available hit points.
Undercommon is not showing up in the lists of language options.
I thought the customizing you're origin allows you to add a feat to any race? Did I misread that somewhere?
There are a number of issues with the Ranger Optional Class traits.
At 1st level, Deft Explorer gives Canny. The skill selected here should get double proficiency bonus, so basically expertise. ("Your proficiency bonus is doubled for any ability check you make that uses the chosen skill.") It only gives proficiency at present.
At 6th level, it should give Roving. This is not showing in my list of class features. It has given me a climb speed and swim speed, but it has not increased my walking speed by 5.
If I activate Primal Awareness, it does not display as a class feature. Primeval Awareness, which it replaces, still does. It does add the relevant spells to my spell list though.
Favoured Foe description shows "you can increase that damage by scalevalue - No level scale data available." If you click into it, it shows the correct levels of damage.
Despite having taken Favoured Foe, which is supposed to replace Favoured Enemy, class features is still showing Lvl 6 Favoured Enemy selections
For the monk optional class feature, Dedicated Weapon, will there be a way to set the dedicated weapon on the character sheet? For example, I'd like to set darts as my monk's dedicated weapon, so that the sheet accurately reflects it as a Martial Arts weapon.
Thank you!
I don't seem to be able to adjust ability score increases (using the custom origins tab) granted by subrace selection.
I am having the same issue as @mukmaster above. I have the class features turned on but it will not populate.
Favored Foe is busted.
Shouldn't the Aereni Wood Elf race be allowed to move the +2 dex and the +1 wis mod to any stat. It is only letting me move the +2 mod
There is a minor bug with the cleric optional class feature Harness Divine Power in the features & traits section of the character sheet.
You can expend a use of your Channel Divinity to fuel your spells. As a bonus action, you regain one expended spell slot of up to level 2. You can use this feature scalevalue - No level scale data available times. You regain all expended uses when you finish a long rest.
When should TCE show up on the D&D Beyond App?
Are you sure?
Can't seem to find Mislead as a 5th level spell for my Warlock.
EDIT: Make that any of the 5th level spells, the other are there. I did indeed ensure the Optional Feature check was marked, and cleared my cache.
EDIT EDIT: While all spells of lower than 5th appeared originally, once I added the additional spells checkbox in Optional Features Manager, the 5th level spells showed up.
I made a character with a Tiefling subrace. The ability score change seemed to work fine but I noticed the character sheet is displaying both the standard racial increase and the new variant increase at the same time for 6 overall instead of 3
Monk’s Quickened Healing too.
Creating Epic Boons on DDB
DDB Buyers' Guide
Hardcovers, DDB & You
Content Troubleshooting
I've logged out, closed the browser and made sure the "optional class features" are enabled but none show up for existing or new characters
Refresh your app, it’s there now
Creating Epic Boons on DDB
DDB Buyers' Guide
Hardcovers, DDB & You
Content Troubleshooting
I have that same error.