I was playing around, remembering some issues people had with invisible inventory items, and I decided to test some of the issues myself. I found that if I drink a soda and move another item of the same type to it's previous slot, the slot that soda 1 was filling up is 'pseudo-full' being that it appears empty, however attempts to place an item inside the slot are futile. I will explain the process better in steps to reproduce.
I ask that you 'thumbs up' this issue, especially if you can reproduce it, so that the devs can see and will have a basis to begin narrowing down the source of recent 'invisible item' issues.
Thanks for reading!