Problem moving Hyper-V host/guests to new protection server

We have a problem regarding Data Protection Manager and backup of a virtual SQL machine running on Hyper-V.

The setup is as follows:

We have 4 DPM servers running Windows 2012 R2 and DPM 2016 (5.0.361.0) - DPM01, DPM02, DPM03 and DPM04.

Then we have a Hyper-V Production server running Windows 2012 R2 - HPV12.

Finally HPV12 is running 6 Hyper-V virtual machines - among those SQL02.

The problem is this:

We moved protection of HPV12 from DPM04 to DPM02 - no problem.

Then we moved protection from DPM02 to DPM01 - but now we only see 5 of 6 VMs under HPV12 - SQL02 is not showing up (and we did the refresh, in the correct way).

To troublshoot we moved protection of HPV12 back to DPM02 - now we see SQL02. Then to DPM01 again - now we don't see SQL02.