From PlishPlishFish on discord:

slight update on the problems with some items not highlighting and not having their stats parsed
I think it is related to weapon skins. When I switch to holding character compass and click with it, it removes the weapon skin and the item is parsed correctly again. This could be because wynncraft does a /replaceitem and wynntils detects the item stack changed and tries again to parse it (which would go along with picking up and setting down the item in inventory also fixing it because the item stack changed), but I don't really know. Also, I have my output log open and am playing around with this, and I can't produce any error messages (besides receiving passegers for unknown entites, which just happens all the time)
Steps to reproduce:
have a weapon skin selected
click the ground with your character compass to clear weapon skins
hold the weapon and cast a spell successfully
the item highlight and identification order and roll anotations will be gone.
when you want the item highlight again, scroll to another weapon in your inventory if there is one, and both items will highlight correctly. I may be wroung about this sentence, but having an open spot between them doesn't seem to change the behavior.

I cannot reproduce this.