Calendar Type Report shows 0:00 when 'Calendar by' field is not date-time stamp:

1. Navigate to Reports > Create New.
2. Fill in the fields.
3. In the Calendar by field, select one that is not a date-time stamp.
   
   Note that 0:00 is displayed as shown in the screenshot.

There are two workarounds you can try:

Option 1. Disable the new calendar reporting as these timelines were introduced from Helsinki when the calendar reporting was reworked completely.
Option 2. Add a new System Property:
Name: glide.report.new_calendar
Type: true|false
Value: false

By adding this property and setting it to false, the instance will use the pre-Helsinki calendar report where the time stamp will be hidden.