I noticed if you put your controller near or on your shoulder, that the elbow starts to switch positions aggressively with the smallest bit of motion from the rest of the body. This happened with the same behavior on two different body bases, which lets me assume, it is a general issue with the beta IK.
6 point with index.
Hight avatar scale and head-lock.
(need to test it tomorrow if it also happens in on the other settings and will make a video about it)