Sigma 150/2,8 w MMF-3 on E-M5: having trouble

Hello!

Today I received a used MMF-3 and also a Sigma 150/2,8 HSM Macro, in 4/3 guise.

I have confirmed that the MMF-3, mounted on my OM-D E-M5 is doing 100% OK with my Olympus 14-54 & 50mm/2,0 lenses.

But the Sigma, just refuses to set focus correctly. I expected that it would be a slow auto focuing package, no problems with that. But i simply doesn´t set focus, when it stops trying focus is several centimeters off, when for example aiming at a subject some 2-3 metres away. Same thing when aiming much farer awar, say 15-25 metres. No sharp focus achieved.

Tried again before posting this, and can add that it is not consistent in doing front or back focus, both occurs.

Is this a known issue with Sigma 150/2,8 HSM & OM-D, and/or something that is fixable by getting the new firmware for the OM-D (I have the first firmware)

Has the MMF-3 in itself shown some problems, or is it working exactly as the MMF´s that came before it?

I am thankful for any input on this, before I will contact the seller (who used the same combination, he has a OM-D too)

Aim & Frame