Problem in Calibrating Red Channel using Red Sky Flats

[Eric Dose]

That might work, as PixInsight should convert everything to 0-1 scale, flats and target images both. If your later steps can handle 0-1 scaling, you may be in business.

But using PixInsight-treated images in MaxIm (which doesn't know what to do with 0-1 scaled images) would likely end in tears.