log: https://pastebin.com/zXJQf8tT
video showing issue: https://www.youtube.com/watch?v=VHR3M0DhbCA

When having items in a shulker box larger than normal using quarks "right click to add" feature it deletes any items that exceed the standard inventory size of shulker boxes.

I am:
running on latest version of all mods
running only quark (and its dependencies) and iron chests
playing MC 1.12.2

I was just about to create the same issue

And this was STILL never fixed. With everyone in the discord being as useless as dirt.