After update I have an Inventory Tweaks mod bug. When I press R it sorts correctly but only visually because when I try to pick up any item with my cursor it desorts again (I'm using MyM launcher). Here is a video: How to fix it?
I've had this bug before, go to the 3 dots in the top right corner of your inventory, more options, and disable server item movement. Don't know why, but that fixes it.
That's my guess too. Since the server doesn't have item movement, it overrides it. So just disable that and you should be good. Why was inventory tweaks taken out anyway?