Meeting create form: duplicate from field is not always usable

[MSoeb]

Describe the bug
It can happen, that the 'duplicate from' field is grayed out and a reload is needed to made it usable.

How to Reproduce

1. open an instance
2. create a committee
3. create a meeting and set it as template
4. create a new meeting a try to select the template from the 'duplicate from' field. > If the field is not grayed out, reload the page until it is.

Expected behavior
If an account has the permission to use the 'duplicate from' field in the meeting create form, the field should always be available and useable.