Been following this thread and was just looking to see if there was a conclusion.
I’ve applied a bit of logical thought, sometimes I’m wrong and sometimes I’m spot on. I have no expertise at all in this area.
Seems to me that your ABS is checking the wrong wheel therefore inducing a slide rather than correcting one. To do that it must think the wheel it is checking is rotating disproportionately quickly compared to the other. Logical conclusion; it doesn’t know where your steering wheel is.
Now for the bonkers. Choose a cold morning, wrap up warm, switch the heating off, wind all the windows down and drive. If the problem persists longer my money is on the slipper ring. Not sure how you prove it though. If it doesn’t know it’s wrong will it log a fault? Do you have VCS on your PC?
Edit, missed a bit. I’m thinking your sensor is not detecting the full angle of turn until it is fully warmed up. Therefore the ABS thinks it’s more straight ahead than it actually is.