RGB stacks clipping blackpoint

[woldsstargazer]

My RGB stacks in Astroart have started to clip the blackpoint prior to any processing.
Luminance stacks are fine. Trying to understand what the issue is. Any suggestions welcome.

[fabdev]

Hello, verify if the dark frames are the correct ones (duration, temperature) of each R,G,B sequence.
As a test, try disabling the option "Remove negative pixels" in Preprocessing.

[woldsstargazer]

Thanks for the negative pixels tip. Will try that. Darks all matched ok.