When trying to smelt cobblestone in a crucible an error appears when the crucible is focused (Hwyla/TOP). The cobblestone seems not to smelt. If you wait for a while and try to pull lava out, the buckit will not have lava in it.
Running the server world on client showed me: it worked there and the cobble was about to smelt.

This only appears on a server, client side works pretty fine.

To Reproduce
Set up a server, join world, build crucible and click cobblestone into it.

Expected behavior
Smelting cobblestone like it does client only.

Version
Minecraft Version: 1.16.5
Forge Version: 36.1.16
Ex Nihilo: Sequentia Version: 2.0.2.6 (5/1/2021)

I did not find a log entry for it, neither in server nor in client log.

can u screenshot the error?

Place a crucilbe
right-click with cobblestone in hand

Error appears, no smelting visible

Hope it helps

It is a pity, but I'd say if you can't reproduce it there is nothing you can do. I fear this might be caused by any other element outside of ex nihilo.

PS: Of course, there is a heat source beneath the crucible ;o)

I've followed the steps that you've given, but I cannot reproduce it. Also, you don't have a heat source below the crucible which is why its not melting the cobblestone.