How to reproduce

• go to the demo : https://demo.ametys.org/nightly-intranet/projects
• add an event to the calendar
• Choose an end time by selectiong the scroll
  

 It's impossible to scroll down; it disappears

• another test
• create an event with a date in the following day
  
   * Choose a start date and an end date using the scroll bar
  

The scroll bar disappears when you select the end date