Sorry.....must be something strange. I don't have an issue with it in my desktop Premier.
I did note, that when I have a simple 19 entered, and it gives me the error, then, when changing it to the proper 2019 format, that the wrong date error doesn't disappear until you click in another box.
I was wondering if it could be some kind of OS system setup conflict. I haven't messed with my W10 date format settings (or even if I can) but on one of the older Windows (98?) you could use a different date formatting layout for your OS. Don't know if that would conflict or not.
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
