Minecraft Version 1.12.2

Forge Version 14.23.2.2611

Mod Version 0.4.0-136

Describe your problem, including steps to reproduce it

When PneumatiCraft is installed together with Ceramics, it causes Ceramics' Clay Buckets to turn into Iron Buckets when picking up any modded fluid. As out of all the 245 mods in my pack only PC:R causes this strange mod interaction, I believe that the issue is on its side (somehow).

Yep, PNC:R was at fault (some code ported over from 1.7.10 didn't make sense in this environment). Fixed now.