Repro steps:
Go to the "New Experiment" page.
E.g. https://developer.playfab.com/en-us/r/t/AAAAA/analytics/exp/in-progress/new
Enter the "End date & time (UTC)" field by clicking the year.
Type [backspace]
Result:
Blank page
Alternative:
Selecting the last two digits (e.g. "22") and typing "9" also causes this.
Probable cause:
The year "202" and "209" are too low for the internal Javascript logic.
Software:
A very up-to-date Chrome on OSX
PS: None of these topics are available in this forum for selection: experiments, website, portal, console, html, playfab itself. I chose "analytics".