Using 1.12.1 latest forge and replaymod. The game crashes when I click the disk button to render when using "S&K Photo Realism 512" resource pack. Works fine with lesser resource packs. I get this error:
The game crashed whilst calling gui method
Error:java.lang.IllegalStateException: Cannot convert position unless rendered at least once.
I'm assuming the gui element isn't loading up fast enough due to the high res? Just a guess.