I've noticed this issue since the TG DLC dropped. Its not S dramatic as the title suggest, but its driving me up the walls. Its almost as bad for me as trying to decon items and comparing that list to what I want to research (there being no way to see what you got researched already when looking at your items)
ANYWAYS
I noticed a new issue when depositing items to your bank. Basically, when your bank is full, like in my case 100/100 it seems like I cant deposit any stacked items like I was able to do before. So say I got a full bank of 100/100 and I want to add 1 more "Hemming" to my already stacked 20 items to bring it to 21... I can't.
The engine only checks if I got 100/100 and disables deposits accordingly. This forces me to withdraw an item from the bank to reduce the total to 99/100 then add my stacked item(s) which was my 1 "Hemming". After I added it I obviously still sit at a total of 99/100, then I can deposit my previously withdrawn item to bring the tally back to 100/100.
TL;DR : you cant add to existing stacked items in the bank if your total space is maxed = bug.