Powershell Windows defender bug
I found a bug with windows defender cmdlets!
Providing an argument in format HH:mm works for values from 00:00 to 16:59 works as expected and when running get-mppreference the scanscheduletime and scanschedulequickscantime fields show the time requested.
Providing a time past 7pm (17:00) and then running get-mppreference shows the time in the format 2982615.22:16:00, which i believe means ~3 million days in the future.
windows 10 enterprise build 171314
windows server 2016 datacenter build 14393
Please let me know if you would like any further details!