FM19 default Java Calendar - cannot access all fields to configure calendar

A very strange problem.

I added the default Java calendar supplied with FM19 to a solution. While I can assign the fields from the calendar table to the "required options", I cannot assign the fields in "optional fields".

When I open the drop-down in the "All day field" and "Editable field", they remain empty.

When I open the drop-down in the "Event style field", I only get this selection:

Any ideas how to solve this? 

Thank you.