GL viewer does not render the volumes on macOS 10.14.2 and I get a grey window as shown in the attached.
$ cd $ROOTSYS/tutorials/geom
root  .x rootgeom.C
root  gGeoManager->GetTopVolume()->Draw("ogl")
But the volumes are rendered right after resizing the window.
I think this bug appears only after upgrading macOS from 10.14.1 to 10.14.2, but I am not 100% sure because I do not have a 10.14.1 machine. Rebuilding ROOT from the source didn't help.