When changing SC Time Format (Settings > Interface > Time Format) to any of the 24h formats, then SC is unable to set the alarm time on a boom.

The BOOM is able to set the alarm time and have it save in SC.

To Reproduce:
SC > Settings > Interface > Time Format: Select any of the 24h settings (#5 works all others do not)
Click Apply
Switch to Player > Alarm Clock
Click ADD ALARM
Enter a time in the Alarm Time box > Click TAB to change focus 
Click APPLY: Notice that the time will switch to 00.00.
Check the BOOM and notice that the Set Alarm time is 00:00
----
Change the Alarm Time on the BOOM: Notice that the alarm time is correctly set and reflected in SC