Mekanism-1.16.1-10.0.8.431.jar
MekanismGenerators-1.16.1-10.0.8.431.jar
MekanismTools-1.16.1-10.0.8.431.jar
Forge 32.0.106

Haven't seen any Mekanism ores in a few hours and JustEnoughResources does not add a world gen tab to them either, so they must be broken.

Is this in an existing world or a new world? Given in an existing world you would need to enable retro-gen if you want them to spawn in existing chunks. Also I don't believe JER has support for any modded ores without running some command to analyze a bunch of chunks.

I just started today. I am 90% sure I didn't start the server up unmodded beforehand.

However, the first run crashed due to a BetterSprinting issue... maybe I've got into some weird state.

I created a new world using the same setup and Mekanism ores were there, so sorry for a false alarm.

I enabled retrogen (#3513 (comment)) so hopefully that fixes my current world.

One thing to note about enabling retrogen is you also need to bump the "world gen version" (don't remember the exact wording of the config name) to something higher than one in addition to enabling retrogen so that it happens in pre-existing chunks.

Yup! It worked.

For people running into this issue at a later date - what needs to be changed:

world.toml

enableRegeneration = true
userWorldGenVersion = 1 # Increased by 1 from 0

Seems like the retrogen happened at a cost though... it messed some chunks up in a weird way where hundreds of blocks are missing.

I think there may be something more/odd going on with your world in general given how retrogen is setup it replaces stones with our ores and isn't able to replace them with air.