After another 30 minutes it finally failed on its own. I then tried to re-publish and this time it failed much quicker with the following error:
Fault type is UNKNOWN_FAULT_FATAL - After waiting for 300 seconds internal template VM: vm-855 is still not powered off. Giving up!
So nothing super helpful but at least it's not just sitting at publishing anymore.
Make sure your releasing the ip at the end of updating the parent, if you don't I've seen similar messages.
I re-snapped it after doing an ipconfig /release and I was able to push the image successfully so hopefully that resolves the issue going forward.