wrong date

Hi! It´s my first thread in this community so I beg your pardon for any faults on my side.
The date-changes do not work properly any more. rename a file 'date-added' or 'date created' makes it "1980-05-18".
Any ideas what may cause this?
Thanks in advance and my regards Frank

Select the file in Finder and do "Get Info". Check what the dates are there. Alternatively, use the Rule Status interface. Click the "i" button for the file to check all the date values. My guess is the date is empty.

Thanks for supporting me!

I figured the following: I renamed a folder "inbox" into "InboxProjects" - every file hazeled in this folder got the wrong date (date created shown in the finder-settings the same wrong date as after hazeling).
I created a new folger "Inboxnew" and Bobs your uncle - I do not understand it, but I am glad it works, for now at least. Maybe it is of interest.
Best Frank