I wasn't able to get any of our new 2018 i9 laptops enrolled using DEP. I fixed it by using Internet Recovery to reinstall macOS. Internet Recovery pulled the 17G2208 build of 10.13.6 which includes the i9 throttling bug fix. DEP is working now. The laptop originally shipped with 17G2112 which doesn't work to get enrolled to DEP.
Exact Spec Laptops being tested: 2018 MB Pro 15", i9, 32GB, 512GB
