R5 IBIS seemingly erratic behaviour when shooting video

Nov 23, 2020
Hi everyone,
My R5's IBIS seems to behave in a weird way when shooting video with a Canon EF 24-70 f/2.8 zoom attached (this lens has no IS). Even if I'm just "smoothly" panning handheld, the sensor moves around in short, erratic, unexpected bursts. Very annoying and of course renders the footage useless. I have tried different settings (digital IS off/on/enhanced), recording modes (auto/manual exposure) and AF methods, to no avail. Basically, I've had to turn off the IBIS to ensure I get my 4k footage jitter-free. On the (also non-stabilized) EF 70-200 f/2.8 the problem is much less noticeable. Has anyone run into this same odd behaviour? Any fix suggestions?
Nov 5, 2021
I had a problem like this just recently with my R5+EF-RF adapter+1.4TC+100-400mm EF IS L II lens. I've commented on another thread regarding this (https://www.canonrumors.com/forum/search/475093/). The preview image 'shake' was really violent and the screen also seemed to show ghosting from previous preview frames (like 1-2 sec prior). Definitely associated with IBIS as it didn't occur when IS mode was switched off. I didn't think that this was a problem when actually recording video, but it was (though seemingly not as bad as in preview mode). When I got home I tried my RF 24-105mm f4 lens and could still see the problem, so I initially though I'd be heading for a warranty repair, but as per the other thread, I now seem to have fixed this (wrench(5)->reset camera->basic settings). Someone else commented on that other thread that they had had the same thing. I've uploaded a zipfile of a video clip showing the problem ( .mov files aren't allowed as attachments..).