Individual sub-type custom fields don't appear in online event registration

Hi, this is my first bug report so I'll my best to describe the problem I experienced.

Discovered this on my site after upgrading to 4.5.2, and it persisted after updating to 4.5.3. Was also able to replicate it on the demo site.

When selecting profiles to be included in an event's online registration page, any profile containing custom fields related to Individual sub-types do not appear in the drop-down menu.

When I select the 'Create' button for including a profile in the online registration, I can see the custom field set I created for the Individual sub-type listed on the right side of the overlay window. But when I click to expand it none of the actual fields are displayed- it just looks like an empty field set.

This means that any profiles I created in earlier versions that included data from an individual sub-type are no longer accessible for any of my event online registrations.

The attached images show what was recreated on the demo site.