Edit: Holy smokes, it was all just a browser issue. Using Firefox now and no issues.
I'm having serious problem like @cyberco, although mine seem a bit worse.
Updated to 13.0.6.6, and now can't even view extensions. Receiving errorCan't Load Local Endpoint Manager Directory!
Tried uninstalling and removing OSS Endpoint completely, and can then view extensions.
Reinstalled, same problem comes back (and now don't have lost my configuration, but can rebuild that I guess).
Tried importing packages and extensions csv manually, but new version cannot upload these files or set any other settings in fact as has been mentioned previously in this thread, so doesn't seem working for me.
Now on beta version, but same results as above.
Next up I've tried a new install like @tm1000 suggested, but same problems. I installed OSS EPM first, and checked (same issue). Then upgraded other modules and still the same problem.
One other thing that may be of note, when trying to uninstall it on my production instance, I receive the following (although does appear to be uninstalled).Error(s) removing endpointman: Failed to run un-installation scripts
Is there a way of perhaps installing the old version manually from before this started happening?