Just updated from PSE 11 to 13, used to be able to mark faces but now when I click on the "Mark Face" button it analyses the photo, says there are "No new people found in your selection" but won't allow me to mark them manually.
I have the same problem, and here is what I do:
1: Pressing "Add People"
2: Runs "People Recognition"
3: "Analyzing Your media now"
4: "No New People found in Your selection"
5: Press "Mark Face"
6: displays "People Analysis is yet to be performe on the selected media. Would you 7: like to start the analysis now? Yes No
8: Pressing Yes
9: and it is back to step 2
Upgraded from 11 to 13 at X-max. Updated to 13.1 yesterday. Win 8.1, 8G memory
(Have tried to rename breezesession.dat, and access rights seems ok. File reappears when Organizer is used.)