description of the issue. The moment that I go to use the skyhook it triggers a concurrentmodification exception. Just to help there are 2 mods active Optifine HD_U_E3 and immersive engineering. running version 0.12-91, forge version: 1.12.2-14.23.5.2838-universal

Crash report link: https://gist.github.com/DDX5/73dc2354356c734145168198ed31f5c6

We usually don't support OF, but I think I know what causes this issue and how to fix it. (Note to self)

Ok that's great sorry for not being on for a couple of days my network card is playing up