Minecraft Version

1.15.2

Forge Version

31.2.36

Mod Version

pneumaticcraft-repressurized-1.15.2-1.4.4-64

Describe your problem, including steps to reproduce it

This one is easy to reproduce, adding the four ingredients into the pressure chamber with a hopper the bucket does not go into the chamber. Break the chamber and add the bucket manually the message no valid ingredients.

The ingredients are: a bucket, 2 gunpowder, 2 spider eye and 2 rotting flesh.

"a bucket" ? Double check the recipe: it's a bucket of molten plastic :)

Sorry, it looked like an empty bucket, sometimes I'm blind.

Why plastic instead of water? If it is to gate PCBs behind plastic, it doesn't make sense as you need plastic to make the Amadron tables and empty PCBs.

Etching acid has always needed plastic to make, although in earlier versions of the mod it was Green Plastic items, rather than a bucket of molten plastic. Otherwise the requirements are very similar.

There is something that you could do, molten plastic is grey and plastic is white how hard would it be to make molten plastic a lighter colour?

Yeah probably not a bad idea.