I have the new 100-400 lens on my XT10 and really am enjoying it but one frustrating thing is that, when you zoom the lens either way, the connection between lens and body has enough play to disconnect the viewfinder and presumably all electrics.
One minute you are zooming from 100 to 400 and the next the viewfinder goes black until you zoom a bit the other way again to reconnect. The stiffness of the zoom is probably a contributory factor. I'm sure I'll live with it but it is annoying and not really something that should happen.
Probably hard to tell if the fault likes with the lens mount or the camera mount!
Anyone else noticed the same on XT10 or XT1?