EM5 Mk2 focusing issue with Pana 100-300

Just wondering does anyone use this combination and experience any focusing issue, especially at the long end (like 200mm and up)?

A few weeks back I was trying to take pictures of airshow and I kept having problem with the camera focus hunting most of the time, especially at the long end of the zoom. On that day the weather was a bit hazy, and I thought perhaps the haze is the cause. The day after I switched to the Oly 40-150 Pro, and that seems to improve things a bit, mind you the haze was slightly better on that day.

Yesterday, I was trying to take picture of the super-moon, and before the moon rise, I tried to take pictures of the city skyline, and even though the weather was good and the sun is still up which gives the buildings a good contrast, the camera still have issue trying to focus at anything. Again the problem disappeared completely when I switched to the Oly 40-150 Pro. And later in the night, I again tried at night when the city lights are on and again with the Pana 100-300, the camera struggles to focus to the city light.

Up until a few months back I was using this Pana lens with the Oly EPL1 and from what I remembered the combination was much better with the autofocus for skyline pictures. I have not used the EPL1 that much since I had the EM5, but I will probably give the combination a try one of these days to try see if the E-PL1 is also having the focusing problem with this lens under the same condition.

I'm wondering is there any setting that I'm missing on the EM5?
Or perhaps there is some firmware update that I'm missing for the Pana lens?
The lens I believe is still with the original firmware that came with the lens when it was first released, and the EM5 is also still with the original firmware from the release.

Thanks in advance for any comments and/or suggestion.

Yes. Its the lens not the body.

That lens is in dire need of a refresh (and a focus limiter).