Don't bother with PreSonus technical support... they don't know their own stuff; that being out of my system... try the following:
Go over -> Options/Locatiosn/VST Plugins and click the "Reset blocklist" button, make sure the checkbox "check on startup" is set, close S1 and restarted after a few minutes.
Hope that works for you as it did for me.
Regards,
JB