Anyone experience IS malfunctions during Live View?

Hi,

I started noticing some weirdness with IS while using Live View on my 5D3. Wondering if it's a software bug?

I first noticed when I got my 70-200 2.8 IS II back from Canon for repair, along with my 2x III extender. While testing with Live View I noticed that with the extender on, the IS would not activate as I auto-focused. But with just the lens bare it worked fine. Non-live-view everything worked fine too. A few weeks later all combos worked as expected.

Now, I just tested the same 70-200 with it zoomed in 10x in LV. IS would not work. Again, non-live-view works as expected.

My 24-70 f4 IS also works really weird, and has always done this since I got the lens. When zoomed in 10x, at macro distances, IS is on even when I am not auto-focusing or pressing any button. But then when I press the AF button the IS shuts off. It appears that when not zoomed in or(?) not at macro distances the IS works as expected. And again, when not in LV it works fine.

Is there some weird menu option that changes how IS works during LV that I might have changed (or Canon changed) by accident?

Thanks!

I don't have either of those lenses, but that sounds weird. All my IS lenses work as I would expect on all my cameras (on with AF pressed, no difference in LV zoomed in or not).

I believe there is a recommended sequence of mounting the lens/extender combo to the camera. I'd check the manuals. Having said that I think you mount extender to the lens first, then the combo to the body. I'm not positive on that as I don't own the combo, just working from memory.