StackUp does seem to break quantum backpacks, but I have no idea why and I couldn't get StackUp to run in my development environment so I wasn't able to investigate any further.
The regular backpacks appeared to work fine, so a workaround might be avoid using quantum chests and just duplicate your backpack(s) using ender eyes instead.
UPDATE: I tried the same with a clean unupgraded backpack and the saame problem keeps happening, not sure what could it be anymore :/
I have a problem, I installed StackUp! and expanded stack limits to 1k (1000), I made a quantum backpack and after collecting and opening it I noticed some of the items that should be around 2 or 3 stacks of 1k in it (like cobblestone) were absent, in fact I tried moving more stacks into it and they just disappeared, I reloaded my world and still nothing, not sure if it was a compatibility issue.
0
Excellent! You have saved my build's life, thank you!
0
UPDATE: I tried the same with a clean unupgraded backpack and the saame problem keeps happening, not sure what could it be anymore :/
0
I have a problem, I installed StackUp! and expanded stack limits to 1k (1000), I made a quantum backpack and after collecting and opening it I noticed some of the items that should be around 2 or 3 stacks of 1k in it (like cobblestone) were absent, in fact I tried moving more stacks into it and they just disappeared, I reloaded my world and still nothing, not sure if it was a compatibility issue.