In the latest 1.14 snapshot shift-clicking the destroy item button and /clear only remove items that are in or had recently been in a players hot bar. 

Here is a video demonstrating the glitch: https://youtu.be/OVNHTKRYu_Q

Hope this helps!

I saw this issue for the 1.13 snapshots but do not know how to re-open it and it is slightly different.