The calendar used to select airtime in Content Scheduler hides after every click.

Steps to reproduce:
1. Create a Page.
2. Drag a C. Scheduler block to it.
3. Open the block's settings, Select Content, choose any Content item and Confirm.
4. Click the Date & Time box.

Result: Each click on the arrows for setting hour and minutes closes the calendar (so you need to open and close it multiple times to set a time e.g. 6 hours in the future).
Also, it is impossible to simply type in the time.