[1.20.1 ]i have tryed to open both old worlds from before mod was added and new world creation and after the percent reaches 100% it will stay like that infinitely.
this instance of the game has a lot of other mods other than electrodynamic mods, this fixes itself after electrodynamics is removed from the mods folder

This is the crashreport that appears after the game is closed with task manager (the game can not be closed normally)
latest.log

I see nothing implicating Electrodyanmics or one of its dependents in this log file.I do see some performance mods installed which doesn't help narrow down the issue either. We need more information than this unfortunately.

Does disabling ModernFix from loading help?

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