Date Time field 12hour format

[Deleted user]

I'd like to have the ability to change a date/time field after a ticket is created from 5:30 AM to 5:15 PM.

I can manage to achieve a time of 5:15 PM when I manually type 17:15 PM into the field, if I type 5:15 PM the field turns blank.

I'm unable to see anything obvious within General settings > Advanced settings > date/time settings or within the Look and feel settings