Tested and Confirmed, not sure if its a bug with Pipez or even Create Itself.

Originally Reported Here

Functional Storage Version: 1.5.3

Titanium Version: 4.0.40

Does this happen with drawer like items like mekanism bins or sop barrels (stuff that can hold items that cannot be stacked in one slot)

Just tested with a meka bin and the number is lowering as expected.

Also, testing with a MI Barrel, the number does not increase but it also does not decrease O.o

One more test, with Sophisticated Storage's Limited Barrels, this seems to also behave like it should, no dupes.

This should also be reported to pipez, they simulate extracting 4 items but they execute extracting -2 items. This happens because they try to extract more than the stack size of the item and the output can only accept 1. I mitigated it on my side by forcing the max stack size when extracting.