Tested the OMD EM1, Kipon EF to MFT adapter, and the Sigma 150-500 f/5 combination. Last time I tried, it didn’t focus, and sometimes the camera had the “no lens” symbol on the menu screen.
The latest firmware update has since fixed that. Singing Honey Eater,
Just have to remember to switch the IS/OS off on the lens, as it will ‘jiggle’ the image if it’s on, as the EM1 has in body stabilization.