If you can't see the crew images then most likely your Global password is within 15 days of expiring and the app should be telling you this already. The fix is to go to http://flyingtogether.ual.com and update your Global password. Notice I said go to http://flyingtogether.ual.com and not some other place. There is a percentage of users who think that going to Flying together via CCS is the same thing.
Once you password issues are squared away, some user find they must touch Crew Look Up from the main screen of the app then touch Delete All.
If this doesn't work then contact me BUT, tell you have checked your Global password (about half that people that contact me think they have fixed their Global passwords but have not).
Tell me WHAT pictures you can't see. Examples are, I can't see the crew images when I touch View All, I see a ghost images instead. I can't see crew images when I use Crew List. I can't see crew images from open flying when I touch on a name. Also tell me if Apple or Android.