When the Quark Backpack is equipped in Valhelsia 3 and the Player tries to craft something in their 2x2 inventory, the game crashes. When the backpack is unequipped, the player is able to craft there again. I hope this issue isn't known yet and this is helpful.

Best regards
Dave

(Heres the crash report, i hope this helps too)
crash-2020-11-08_21.16.44-client.txt

This is a crash related to Fast Workbench, not quark.

This issue was reported to both issue trackers and each of you has said that the other needs to fix it, but Shadows has mentioned a potential fix that would need to be made on the Quark end. Shadows-of-Fire/FastWorkbench#54

I'm hoping that you two can chat if needed to get this incompatibility fixed since people have been reporting the issue to us on the Valhelsia Discord multiple times per day recently.