I had the same issue.  In my case, it appeared that upgrading from 1607 (Anniversary) to 1703 (Creators) via Windows Update did not allow the OS to retain the OEM license status.  Instead my activation state was Activated with a digital license, not the OEM product key I'm used to seeing.  

Along that same line, I'm guessing that Image Assist will likely need to be updated to support a capture of 1703 since IA's last revision predates the OS upgrade by 4 months.  I'm no expert, but I don't expect Dell to support an image capture of  Creators Update via IA until Microsoft certifies the upgrade as Current Branch for Business. This won't likely occur until July or August.  My timeline could be way off, but its where my expectations are at the moment and this allows me to shelf this project for a few months.

For good measure I also attempted to upgrade my reference machine from 1607 to 1703 via the MCT.  This too was unsuccessful as the upgrade could not complete.  It runs through the download and install of the OS only to fail somewhere along the line and roll back to v1607.

I also have the same issue. the setuperr.log file says "ClipCleanUpState resetting WNF_OLIC_OS_LICENSE_TERMS_ACCEPTED failed with NTSTATUS=c0000022"

I concur with the other poster that we may need to wait for the Creators Update to reach Current Branch for Business status.

-JP

Disregard, I didn't realize I was capturing a non-UEFI, Gen1 VM.

I rebuilt the VM and the capture went through fine.