HPDM imaging limit

Hi we are doing a mayor upgrade of our Citrix enviroment and tried to upgrade all T520 to the same image build WES7E-32 14WWETGE301 Image Norwegian (May 2016).

We have never had a problem before so  I was woundering if HPDM has an issue when 20 thin klients are imaging at the same time or if their is a hardware issue based on which batch then T520 came from.

For the T520 clients that failed I used the same image on a usb memory stick and it worked fine.

Any suggestions why it did not work.

Thanks Hans Petter