When I am using the compression upgrade in a chest, I am able to see all of the blocks I can pull out but when pulling out for example the non-compressed block, it doesn't lower the other blocks but it increases them.

1st:

After ctrl + shift right clicking

Backpack holding the dropped blocks

I am using All the Mods 10 version 2.47

I am not able to recreate this. Are you able to do so with a new barrel / compression upgrade?

Yes I am. I now have over 300,000 9x cobblestone. Tried it in a oak netherite chest, oak netherite barrel, and an oak diamond chest. all with the highest stack upgrade. When removing the compression upgrade from the chests side bar, it also dupes the blocks just not as many.

I am still unable to recreate. I am trying with the same version of the pack, tried with max stack upgrade, tried with certus quartz specifically that you have there, tried with higher stack of compressed so that I have a lot of uncompressed quartz, removing, adding, ... Still unable to recreate anything.
Could you give me the exact steps I need to follow so that I recreate the issue you're having?

Thats super strange. The steps are placing an oak netherite chest, putting in 2 stack upgrade tier 5 upgrades, a compression upgrade, and an advanced magnet upgrade. shift clicking a full stack of certus quartz block 5x, then control + shift left click on the certus quartz block 1x. then picking it up with a backpack with max stack upgrade and magnet. It seems to work just by shift clicking a stack into the inventory but not control shift clicking if that makes sense.

Ok, I am able to recreate with ctrl-shift-click, now to find out what mod is adding that functionality. There's actually ctrl-shit click functionality in sophisticated which moves as much as possible of the given slot into player's inventory but that seems to be overridden by this other mod.

So I tried recreating this outside of the ATM modpack but I am unable to recreate in dev environment even with the addition of Inventory Essentials (which definitely has ctrl shift click functionality) and Inventory Tweaks Refoxed (which may have the functionality as well per old Inventory Tweaks feature and requests made on their github). With these two the sophisticated functionality of moving as much as possible of the oversized stack doesn't work anymore and only 1 stack is moved, but there's no dupe happening and not even a hint of something funky happening that I can see in ATM where the stack number changes multiple times. So there's another mod (or more mods) that's required for this dupe to happen.

I know that for the ATM 10 pack it should add mouse tweaks so that could be the mod that causes it. Thank you for trying luckily it isn't that game breaking, at least not for me, so thank you for the help.

It seems to work fine when pulling out items using something like the mekanism logistical sorter.

yeah that will work, but I would still like to figure out what's going on with that mod interaction and what mod is causing it. I asked in ATM to see if anyone has an idea of what other mod may be causing this (I don't really want to go through mods one by one to try and see which one is adding this). I will reopen and see if there's more info that I can get here to potentially fix or at least understand what's causing this exactly

Alright, sound good!