Magnús Karl Kjerúlf

Correction: for method one you just have to move the item to a different slot, no stacking required

For anyone who’s being inconvenienced by this bug since it’s still in the game. You can bypass it by using one of the two alternative ways of quick looting.

Method 1: Take one item, place it in a different stack, then shift single-click that stack instantly. Note that you can’t press shift until you’ve combined the stacks.

Method 2 (Speedrunner method): Hold shift, press hotbarslot (or offhand) key -> click → hotbarslot key → click
You have to do this rapidly enough for your clicks to register as a double click. This will put the stack in that hotbar slot.

This bypass of course won’t stop the inventory from feeling janky for fast clicking players but it’s a good excuse to practice quick looting.