[Solved] Register with extract Ha/extract OII problems

I would appreciate if anyone can provide some advice on an APP integration problem. I’m having trouble understanding the reason why in one of my processed images it looks like the flats (or something else) didn’t register correctly.

Images are from a single 4.5 hour session (California Nebula) using a cooled ASI183MC Pro and and this run included a meridian flip so some lights are rotated. I took flats/darkflats just after finishing the lights so image train and rig setup were the same, darks are from a library I made a few weeks ago and all subs including calibration are matched in temp/gain.

When using the “extract Ha” algorithm the resulting integration looks perfect, but when using “extract OII” the flats or the lights (maybe the ones after the flip?) didn’t register properly or were rotated. The only difference in APP settings are the different extract algorithms.

The results are odd too as I’ve used this same basic procedure (extract Ha then extract OII then extract mono for bicolor processing later) for approx 10 other dso projects before including some that are multisession. So far all of my previous integrations have worked out ok in terms of automatic registration of calibration frames.

I’ve also tried several different APP settings to find a solution such choosing different reference frames, forcing the reference to be before or after the flip, manually rotating the reference frame, checking “flip descriptors in x/y”, restarting APP, using individual steps 0-6 vs the push integrate once approach. All of the resulting images always have the same basic results where the extra Ha looks good and extra OII has problems with registration.

Any ideas on what is causing this problem? Maybe process the before/after flip in different sessions just for extract OII?

Thanks!

Brian