Zed360 skeletons not converging

We are on Zed 5.4.1 -
Our cameras are about 6 meters apart - both set at about 2 meters up with a lot of overlap in their coverage - they are two corners of a 6x6 meter room looking approximately into the center.
No matter how long and how slow we walk around in circles the skeletons will not converge -
they flicker about a lot and at best end up a couple of meters apart -
Lighting is fairly diffuse and bright though there is a bit of shadow about…
Just wondering if this is something that’s known with 5.4.1? - or i guess maybe one of the cameras is not working correctly - any hints about what we can do to track down the issue?
Thanks