Testing our application with VTK 9.3.1 and vtk master (decd60aaf1f975d9264a9fd05445d60eaee1d6c9), I still noticed culling issues; with 9.3.1, the right eye is still blank; under master, under some circumstances (for some viewing positions), some actors completely disappear - but only from the left eye this time.
The workaround as proposed above, namely renderer->RemoveCuller(renderer->GetCullers()->GetLastItem());, makes things work in both cases!
Haven’t had chance to try and reproduce with a small example program, I doubt I’ll have time in the next weeks, but I’d thought I’d report it here anyway, maybe somebody else has an idea of how to “really” fix it instead of a workaround…?