Reported on discord: https://discord.com/channels/385059835206565889/781176112512106556/819380114625790022

Aeonian: Hey @Lythom nice job on the port, I love this mod. I believe I have found a bug. I have removed all other mods and narrowed it down to capsule only.

When I put things in a crafting table, there's a random chance that any items I put in the crafting grid with end up creating a separate stack of items that don't stack with one another. because it appears to be random, the best way to recreate this is to just take pretty much any stackable item, and spam hold left / right click all over the crafting grid.

I am running 1.16.4-forge-35.1.37
The mods version is Capsule-1.16.4-5.0.55

If I can, I will also provide a GIF to show what the issue is.

Hope this helps.

Fixed, to be released in 4.0.56+ (1.15) and 5.0.56+ (1.16)