I get the found date from pocket queries...
but, you may need to look at Tools, Options, General, Method for matching placed, hidden and found caches. Pick "exact match" and enter you gc.com user name, case sensitive.
Hope this helps!
Why is it that there's always one more step...
After you have your correct username in the options tab, then you need to reload the .zip file. The program then reads each cache in the list, matches your username with those who posted a find and only then does it update the found by me date column.