Hello Wil,
If the delay start works then I fear the problem might lie in the time for the teamed nic's to be fully operation on start.
As PXE service are dependent on the NIC they need to run (for example if the teamed nic is assigned to be the PXE IP, then PXE service can't communicate with it unless the teamed nic function is up and running properly, but the teamed nic can't start unless regular Windows NIC configuration is up and running)
This adds a second wait and that causes the PXE service not able to start properly.
This just my two cents, in reality it might be something totally different.