The mod seems to reset the whole world when being added to an already existing modpack.

Log: https://mclo.gs/GiA98iT

It was confirmed that is create ore excavation because when testing with just that mod removed it works fine.

I have had the same problem, no changes are saved to chunks between resets when this mod is installed.

It's probably a mod compatibility issue with some other mod and Create Ore Excavation. Please try removing every optimization and see if the issue fixes itself. If it isn't add the -Dmixin.debug.verbose=true JVM argument and post your log here.

This issue is still open.
Is this still being actively worked on?
I wouldn't want to add this mod to my existing modpack for the above mentioned reasons.