if 1. and 3. works well then I assume the problem is in connection between the "Hyper-V Compute Hosts" and your VMAN. Please try connecting via wbemtest (detailed info here). Use the same credentials that are in VMAN.
If you don't succeed then I suggest that you contact SolarWinds support.
If you are doing a POC right now, our Sales Engineering Team should be able to assist you with any pre-sales support issues like this you may be encountering. I would just sent an email to your account rep or email@example.com to get assistance on this and they'll be happy to help.