red block of pixels

Woops missed your post, sorry.

So are you using darks as well? This seems a hot pixel, did you leave integration in automatic setting?

Yes - full set, darks / bias / flats / dark flats ... I asked in another thread and I think you said that if I did use a full set - then APP would apply the right combinations etc. 

Integration - I chose the option for > 20 frames ... as I had 80+ lights.

Thanks

Interesting, maybe in this case you then would need cosmetic correction as well. This can be found in tab 2, calibration a way down. You switch on the hot pixel kappa checkmark. You then load 1 sub (and your BPM and MD) with that red pixel, zoom in on it and select "l-calibrated" from the dropdown menu on top of the APP window. Do you see it go away? If not you can reduce that kappa to 2.5 and check again (select l-calibrated again). This is a fast way to see if you can resolve issues like this before doing an entire integration.

If it correctly removes that pixel and the rest looks ok, you can try another integration.

ps. you mention not guiding, so you can't dither then either, that is where issues like this will also get solved (although I think walking noise looks different, maybe this is related?).