I encountered an issue the other night where my Metz Mecablitz 58 AF-2 would, in combination with my Yungnuo YN-622C transceivers, stop functioning after a trigger or three. Some investigation quickly showed the issue to be with the transceiver rather than the speedlite, at least in so far as immediate functionality was concerned. The test button on the Mecablitz would continue to work after the combined unit stopped working, and power-cycling the Yungnuo would resolve the issue – no Mecablitz restart required.
Some additional testing tonight showed that things will continue to work as expected so long as you allow the Mecablitz to fully recycle between shots. I think the issue I encountered the other night is that the transceiver is sending a fire signal to the speedlite and then, because the gun isn’t fully recycled and it’s not an actual Canon speedlite, is either getting a signal back from the flashgun that it doesn’t expect – or it’s not getting a signal back that it is expecting. Either way, the transceiver freaks and stops working.
In any case, though this hardware combination is supported by neither Metz nor Yunguno, with some diligence in use, the combination works: just be sure to let the flash fully recycle between shots (which you should be doing anyway).