Been searching here and around the interwebs for the last four hours... finding LOTS of people with the same issue, but NO fix...
WP3.5 & BWPS 3.4.6
NO Akismet / Capcha / 3rd party authentication plugins installed
If Hide Backend is enabled, Admin works fine, however User Registration only refreshes the page to blank fields with no email sent to user. I can confirm this on a dozen sites all configured identically (different content)... doesn't matter what alias I use for registration (tried register/registration/broken), nor if I regenerate the secret key.
This plugin is awesome, but it doesn't do any good to build community based sites if the community can't register!!
And no... turning off "hide backend" is NOT a solution!
[No bumping, thank you.]