I'm using civicrm 4.7.17 on drupal 7.54. Logged in with administrator rights. When I try to add a new field, (admin -> customize data and screen -> custom fields) everything works fine. I create a new set, no problem, but then when I add a new field to the set, and click on save, it just hangs, loading forever. This seems to be a new thing as I've created lots of custom fields before.