I've just done a fresh install of FMSA 12.
It worked fine, I uploaded databases to it via the console, turned on Progressive Backups (valid path) and SSL Encryption. Shut down the server and restart it to enable encryption, and it simply refuses to start.
The Admin Console just hangs with a spinning blue wheel. I've force quit the admin console several times now, and tried again. No dice. No error messages, nothing.