[Calendar] Filtering on date does not work

[mastropi]

Date filters defined by the calendar are NOT applied to the request sent to the backend.

Kibella interface version: v3.4, 28-May-2020

Screenshots

[mastropi]

A possible reason for the calendar filter not working:
There is no place where the user selects the date field to filter on...
So, how does Kibella know which field should be used to filter the data on?