If you use imagew - it clones the disk at the sector level - which means if your original build was built on mbr and bios then it is going to deploy that way. Surface hardware requires it to be gpt and uefi. This means that you need to recreate your base build using gpt and uefi if you want to continue using imagew.
The alternative would be to switch to dism.exe (instead of imagew) which is file based and allows you to convert the image from mbr to gpt as part of your imaging work flow. You would have to recapture your image though using dism instead of imagew.
On a side note - dism is recommended for Windows 10 over imagew, so long term you should look at switching anyways.
Hope this helps,