VPCamera turns black in Multi-User VR

we are working in multi-user with DoP, Director and Art Director (in vr-mode) and Sequence Operator (normal mode).
It happens occasionally that our (VPcamera which was created by DoP in vr-mode) turns black for every vr-user, when our sequence operator stores the transform keyframes in the sequencer.

Since the shown camera picture in VR comes from the cameras dynamicly created rendertarget, we can just guess that somehow the reference to the rendertarget just gets lost during these steps. But we can’t tell for sure and hope that someone came across the same problem and might have some tips or a solution.