https://pastebin.com/SLrZDsi2 <- Log file

https://minecraft.curseforge.com/projects/ferdinands-flowers <- mod in question

Ferdinand's Flowers adds a new chest that is very large but limited in which items it can hold. Quark's sort button appears on these chests, but when clicked, some of the items vanish from the chest. However, after emptying a previously sorted chest by hand and then breaking it, the seemingly destroyed items are spilled out. (Apologies if the issue is entirely with the other mod and not this one)

It appears that it's hard to know precisely what the issue is, since that mod doesn't have source easily available.

The same issue happens with Tinkers Construct Pattern chest, maybe is easier to find a solution targeting an open source project, I can open another issue for TiC if desired

Fixed in 4e957aa