I sync two Iphone to one Mirror - one is fine the other not

Hi Community.
I am confused about my new Device. I have installed the MYCLOUD App on two different Iphone (5S, 6) both running with the last IOS. My Wifes Phone (6) run without a Problem and the Photos are on the Mirror like it should be. I can see latest uploads in “Activities”.
When I do the same setup in my Phone (run as Admin on Public folder) I get “in Progress” for days and nothing happens.

I have changed it than to a non-admin Folder, took off the DNLA Media and used the same setup like my I have taken for my wife. Nothing changed!
I have deinstalled the App a couple of times, left it open over night and checked the Settings (background updates, access to Photos, etc.).

Is there any trick to do?

P.S. I can also see that the App didn’t get the full Camera Roll. If I click “upload pics” manually to the WD App, I can see that not all Pics are shown? But there is one photo our of my library that is uploaded all the time in seconds. But only one and always the same.
→ Can it be that there is something with “rights” in my Pics? Where to check?

Thanks!

UPDATE: It came an Update yesterday evening and since that the process is starting. Not all Photos are automatically included into the backup, at least 400 Pics out of 1.200 but the Backup is loading now.