This is a very minor bug, and pretty inconsistent. But It feels like since we got the latest update, It feels like there is an issue with picking up stacks of trophies and moving them.
Randomly the stack is placed back to the inventory, where it was originally being moved from. And to ensure this wasn't user error, I held down shift the whole time, and I tested 2 different mice, and my laptop keyboard.
If you look at this video, you can see on the 9 second mark, and the 21 second mark, that a trophy stack i picked up would go back into the inventory.
I have not tested this with other items besides trophies, however I assume it would do the same.
https://vimeo.com/397003710