This is a strange and very specific bug that I've been experiencing for some months now. The reason I haven't reported it yet is because it's been hard to figure out under what conditions it appears. But I believe I have a good guess after testing it a few times now.
This bug primarily affects voodans who use both the level 9 spell shapechange and a shield. When you shapechange (slaad in my testing) with a shield that that has magical vestment cast on it, something breaks. Nothing changes immediately, but if you log out and back in, your character will have chronic problems with shield vestment not applying AC at all. The only way to fix this is to shapechange/cancel form again, but at this point, the bug will linger and show up as it wants. Only a full reset seems to make it go away completely. And it doesn't matter if you log off immediately after casting the spells, or 4 hours later.
I'm fairly sure that this is related to vestment and not shield parry, but if it helps when investigating this, the character has shield parry. Magic vestment cast on armor is unaffected.
And just to clarify, I'm talking about magic vestment in your humanoid form, not the shapechanged one.
