While holding this wand, you gain a bonus to spell attack rolls determined by the wand’s rarity. In addition, you ignore half cover when making a spell attack.

uncommon (+1), rare (+2), or very rare (+3)

When equipped and attuned, the spell attack bonus at the top of my "Spells" window correctly shows as +10 (+4 wis, +4 prof, +2 wand). Additionally, spells such as Guiding Bolt do also correctly show that their "Hit / DC" bonus is +10. However, Fire Bolt, which I've obtained through Arcane Initiate in the Arcana Domain subclass, still shows as +8.

Character sheet for reference: https://www.dndbeyond.com/profile/Nice_Hipbone/characters/17921665

I have a similar problem with Pact of the Tome.

I am also having this problem, only for me the wand (+1) does not have attunement like it's supposed to and does not apply the +1 across the board (I'm sorlock)

Quote from Eloryn >>

I am also having this problem, only for me the wand (+1) does not have attunement like it's supposed to and does not apply the +1 across the board (I'm sorlock)

 You picked Wand of the War Mage when you need to take Wand of the War Mage, +1.

Good thought but I did pick the +1. However the attunement feature is now working but the +1 still is not working 

Try logging out, logging back in, and waiting 20 minutes. That will trigger the server’s cache to reset. That should fix it.

Where did you get the spells? From regular spellcasting, or from something like Pact of the Tome?

Thanks! I will try that. I have 5 levels of sorcerer and 4 levels of warlock when i picked up the want. I have a homebrew pact that doesn't affect my spells rn.

The Amulet of the Devout +1 (et al) does not apply its bonus to the Arcane Initiate cantrips (same bug as the OP,  except different magic item).

Same issue. My Wand of the War Mage with Eldtrich Blast shows the correct +10, but the Produce Flame and Shocking Grasp cantrips I'm getting through Pact of the Tome show no bonus with +8.