Unable to launch or join coop lobbies

When attempting to host a coop lobby just says "Preparing Game: Reading File List" for a little while and then it stops and nothing happens.

Attempting to join an existing coop lobby gives me the following error: CoopError.txt

Jip and Sheikah mentioned it seems to be a permissions issue, but trying to run the client as admin (which I know is not recommended for other reasons) resulted in no change in behavior. Next step was reinstalling my copy of FA which, again, didn't change anything.