In a SMP world I tried to burn ancient debris in an arc furnace, which caused a client side crash (the server kept running) that did not allow players to enter the server, and crashed their game on attempt. Copying the world however into singleplayer, the arc furnace worked. I am using version 4.2.1 - 131

crash-2021-02-20_23.02.30-client.txt

I just realized I didn't click on immersive engineering's page. Oops.