The full message is
'6/May/22 0:00 AM' is not a valid date. Please enter the date in the following format: dd/MMM/yy h:mm a
Well if I line these up
6/May/22 0:00 AM
dd/MMM/yy h:mm a
The date I am using looks legitimate to me, actually more than the format message thats missing the full am/pm designation.
I would have just reported this as a bug but Atlassian wants a question, so my question is "you gonna fix this soon?"