AC Bug

I am testing a build design for a friend of mine. One of the items in this build is the Spellwoven Robes from The Griffon's Saddlebag Book One, pg. 118. Instead of it setting my AC to 10 + my Spellcasting Ability, it just adds 10 to my overall AC. So instead of my AC being 14, it becomes 24 instead and I'm very certain that it's NOT supposed to do that. 

+1 to this, experiencing the same thing with it just adding 10 instead of 10+spellcasting

Also experiencing this. Tried to homebrew it but that seems not doable 

Thank you and the programming team for your hard work. I'm guessing then that when the Spellwoven Robes is to be used, we'll have to manually override the AC to match the magic item's effect, am I correct on that? If so that's fair and understandable since coding can be very limiting even at the best of times. Again thank you all for your hard work since I posted this last month.