Custom entity reference field on event can't be edited post creation
Overview
I was trying to create an event with a custom field of type entity reference on CiviCRM 5.67.beta1 and after I set that when I went back to view it, the field was empty again (but still set in the database). When I went to test on dmaster I could view the field fine after setting it initially but if I tried to change it I would get an infinite loading screen. See the steps below. I'm not sure if this issue and my original issue are related or not.
Reproduction steps
Create a new custom field of type entity reference, for events. Create a new event Edit that event and try to change the contact in the entity reference field It loads infinitely.
Current behaviour
Trying to change the contact in the entity reference and it won't stop loading
I tried to add the logviewer ext to see the logs on dmaster but it didn't seem to be able to access them