I’m a bit late to this party, but here is my experience so far:
I got the pimax 8k, which worked fine, alone.
I then bought a second-hand base station and vive controllers.
On turning on the lighthouse tracking in pitool the image in the hmd went dark grey and the status in pitool read “not tracked place the helmet in the visible position of the base station”.
I tried some of the usual things, turning hardware and software on and off, following suggestions above about this and that, and nothing worked.
Finally, by accident I discovered that if I hold the headset above and behind my head at arms length, it gets tracked, and works fine.
Every time it goes out of view, or I turn off the headset or pitool, I can make it work by repeating this positional trick.
It equates to having it at standing height about a metre and a half away, facing tha base station.
If I had to guess, I’m a bit too close to the base station to be detected at first (I play sitting in front of the desk the base station sits on, probably only a couple of feet away. This was fine for Nolo, but the vive base station needs a bit more distance.)
Once detected, the close distance doesn’t seem to bother it unless the headset goes out of “sight” under the desk.
Anyway, probably all very silly and noob-ish stuff on my part, but I thought I’d throw it out there in case it helps anyone else.