The SL 3 only allows auto/ Off/other lens setting; the M240, or was it the M9, used to allow any particular lens to be set. Ah progress.
With regard to the M9 and M240 this is lens profiling, different than using focal length info to regulate IBIS. With the M8 your profiling options are either auto or off…no manual setting allowed. The M9 added the manual option.
FWIW the SL2 doesn't seem to apply vignetting or any other optical correction to R lenses mounted via the "official" R-to-L adapter.
stabilisation is blanked out, the lens profile is set to 28 (the focal length. Not a lot more I can do, except go back to holding the camera steady.
This can't be normal behavior. The only time I've seen the Stabilization setting blanked out on my SL2 is when I've mounted an adapted lens with built-in stabilization. With my Leica 90–280mm if I turn off lens OIS the camera's IBIS will still work. The opposite is also true. But with my adapted Canon 70–300mm only lens IS is allowed.
i did see one interesting thing; I had the camera on, went into the menu at the stabilisation point and removed the lens. At the first click, as I rotated the lens/adaptor, the “stabilisation” went from blanked out and unaccessible to accessible. So, I just need to discover what happens during that final couple of degrees twist.
You may want to clean your SL3's mount contacts…and your lens & adapter contacts too if applicable. Otherwise…dunno what's going on there.
-Dave-