COG bounce/ erratic

[TomHalfmoon]

Ref: COG erratic
We were out on the water this weekend and I was able to try a few different options and take some notes.

While underway 5-8 kts. with consistent heading the COG arrow generally moves from an accurate reading to a consistent in-accurate one. Say i"m heading 093, for a short period of time the COG will approximately match 093 and then swing around to say 352 deg. Estimating 20 % of the time correct (093) and 80% incorrect (353) 352. If I change heading the new "incorrect" COG reading will change to a new value but again remain consistent.

With the Autopilot engaged and steering to a WPT the boat will track perfectly to the WPT with a consistent Heading but a bouncing COG.

Question: Doesn't the AP use the COG data to steer to?

Thanks for any suggestions

Tom