Trying to fix it right now. Seems to be an MTA internal web server bug. The only solution is to use the external HTTP server again. Which requires a server restart and some reconfiguration which I can hopefully just do when they fix the old IPs.
Or someone can give you those files that for some reason the internal web server can't send even though I've tried deleting them from the cache and restarting the scripts. The files in the cache are fine it's MTA's internal web server is apparently old buggy crap.