Probably a mod conflict since I have so many mods, but this mod removes the "allow rotten" option at crematoriums for me, therefore stopping my colonists from cremating rotten corpses. Removing this single mod brought the option back.

Not really expecting you to fix this, since I doubt you're having the same problem. Just more of an FYI.

Just in case you want it, here's my mod list:
https://gist.github.com/HugsLibRecordKeeper/e8e62805fd90707bf7f2e10593017697