Is this possible?

[tothandris]

Is it possible for the IBIS to move at 1/400th shutter speed while walking? I've been suspicious for a while but I just did a real test where it became clear that with stitching on (IBIS+RF 24-70 2.8), the image becomes blurry when walking. My camera is an R6 Mark II and I use an EFCS shutter.
The attached pictures show three consecutive photos taken while walking, with continuous focus on the wheel (Camera: R6 Mark II, Lens: RF 24-70 2.8, Focal length: 70mm, Aperture: f/5, Shutter: 1/400th). Only one of the three is sharp, the rest are blurred.
Has anyone experienced this? With R5 I think it's pretty much the same.

Thanks in advance.

 

[neuroanatomist]

What happens when you take the same three shots but with IS off?

 

[tothandris]

Pretty much the same

 

[tothandris]

I have attached the same pictures twice. So the first three pictures are when IBIS was OFF and the second three are when IBIS was ON. The OFF versions are less blurry.