If the flash is used as an off-camera flash, it can be triggered using the remote control system of Olympus. However, only in the TTL mode. Turn it on manually (in the camera menu) The flash will no longer trigger the flash mode. So it is about the slave mode can not be used in manual mode for me. Metz knows about it and has promised a firmware update, which did not come until today.
You can circumvent the problem in which one provides the flash to the servo mode and is thus triggered analog via a light pulse of another flash fires. But again, the manual mode has a quirk:
The flash output can not be used to the full extent in the servo operation. So adjustments are possible only in full career. The 1/3 of jumps, as they exist in the normal manual flash mode, are missing. I mean, the flash output can be changed to 1/2 to 1/4 only in steps as 1/1, not 1/1 to 1/1 to 0.3 to 0.7 to 1/1 1/2 etc ,
I hope this will be rectified, because even the cheap Yongnuo flashes offer as more. Although they lack the automatic and TTL mode, but with manual flashes you have anyway more control over the lighting of the image, which is why the manual mode was supposed to be the mellower.