I can run the polar alignment workflow and capture the images but the PE error does not update no matter what adjustments I made to my mount. I have tried increasing the camera binning and refresh time but to no avail.

Using a ZWO 1600MM/ZWO 174MM guide camera with EQ6-RPro mount and Nextstar Edge HD 8, controlled using a raspberry pi 4/stellarmate accessed from my PC through kstars/ekos.

Any advice would be much appreciated.

Sorry that this is not reliable. My main advice is what you've already done (slow down the frame rate, try binning) as well as "don't choose stars near the edges".
The good news is that this is not crucial to the polar alignment--it is only a UI enhancement. That is, if you move the star (that you recognize visually) to the target by adjusting your altitude and azimuth knobs, then it should be aligned, whether or not it realizes it during the procedure. You could re-measure at that point, if you so choose.

I have toyed with the idea of adding plate solving to this part of the polar alignment (instead of the borrowed guiding method it's currently using to track that star), but of course plate solving can also fail...yes--"why not both?"

Hy

I just took a look at your log. It shows that your polar alignment error was 3.5 degrees.

From the log, it looks like it did track your star for a while (at least in that second attempt that was in your log). Bottom line is that in a situation where your polar alignment error is larger than your image's field-of-view, it can't continue to track the star (because the star will move off of the image at some point). What you need to do is iterate--that is, move in the right direction to reduce your error, and then re-run the procedure, until you get the error small enough so that the star and the ultimate target position are both on the same image.

As I mentioned earlier, perhaps a future implementation will use plate solving that might allow for doing this without iterating, but currently we use a move-the-star correction strategy which requires the target and a chosen star to be on the same image to complete the polar alignment.

Hy