When clear hotbar from inventory, items sometimes remain in hotbar

Steps to Reproduce:

1. Go into creative mode.
2. Get any blocks.
3. Build with those blocks.
4. Try to clear hotbar from inventory. 

Observed Results:
When you try to clear your hotbar, 1 or 2 items will not leave. 

Expected Results:
The items will not leave your inventory unless you do the /clear command.

Screenshots/Videos attached:
Sorry, I don't have any images or videos of this. 

Notes:
This will not always happen, it might take a few tries to work.