You know what, I just started the Workstation Pro VM build and it asked about h/w compatibility.
I totally forgot about this being a thing.
That's probably why my previous VM's built under Workstation Player didn't work in 5.5.
I chose ESXi 6.5 compatibility for this VM and I'm sure I'll be good to go with running it in 6.0.
Or 6.5 if I go that way.
I do hate the webpage mgmt though.