You could try to convert all the column to Date again. In excel, select you column, go to Data tab > Text to Column > Delimited > TAB > At this point you should see a “Column Data format”, choose Date format.
Worst case scenario: Try to change date format in windows to MM/dd/yyyy.
I tried evey date format I found on the forum but nothing worked.
The solution I’ve found is to put the datas on a new Excel file and then ffrom this one I apply a new assign.
I did the same thing as before but with a transition it seems to work.