Just updated to Civi 4.7.22, running WP 4.8, [edited] now running php7.0 [/edit] php 5.5.26
After the upgrade CiviEvent will no longer register contacts for events via the backend. After filling out the details and pressing the ok button, everything greys out - I get a 'processing' but nothing happens.
The green CiviCRM logo isn't turning, the page tab isn't updating, nothing. If I move away from the page I get a warning that things aren't saved (which is correct) but even after 5min it hasn't completed.
I'm about to roll back to CiviCRM4.7.17 which will throw a load of security complaints but at least folks will be able to register for events.