Errors do not appear to be conveyed to the admin interface. My situation is thus, with Foreman 1.3.0~rc2-1 on Debian Testing

Fresh install, clients autoregistering. Had imported operating systems, platforms, etc, but had not set up OS to Partition table relationship. This has the effect of the Partition Table field being blank the host edit page, but not being immediately visible it was ignored until now.

First task was to assign some classes to my managed hosts, but all attempts to save the assignments resulted in the page appearing to have saved, but all settings being lost when the page was reloaded. The host had to be set to 'unmanaged' before any classes could be assigned. Every time the page was saved, production.log displayed...
Failed to save: Ptable cant be blank unless a custom partition has been defined

Upon setting up a relationship between OS and PTable