Multiverse refused to load a damaged world
Applies to Paper, Vanilla.
What it looks like in your log
[Multiverse-Core] The world 'world_nether' could NOT be loaded because it contains errors and is probably corrupt!
What causes it
Multiverse detected errors in a world and skipped loading it.
How to fix it
Restore the world from a backup, or repair it with a region tool.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log