This seems to happen the first time the pack is loaded with OSV, if I close the instance and reload the pack it usually works afterwards.

Forge: 36.1.4
OSV: 6.1
Minecraft 1.16.5

https://gist.github.com/judicius/3876b940ec174906473263e8da312870

This should be completely impossible to occur in 6.2. I'll close this now.

Thanks! I'm aware of this issue. It has to do with asset generation. Assets don't generate every time you start your game, which I believe is why this is so inconsistent. I'll be working on OSV 1.12 again in the next two weeks or so and will take a look at it then.