I did thresholding on HSB channels, now I want to get them back to a single image, and since KNIP can't render HSB yet I decided to do a work around. I use the merger node on the HSB channels, and then convert the colorspace of the resulting image. However the Merger node outputs an image with X,Y,Unknown0 as channels. Now the Colorspace converter can't handle this. Perhaps by flow variable, but I haven't checked yet. Anyways I think the Merer node should just output X,Y,Channel.
How stupid of me, I could just add Channel as a name, and not add it as a channel. Also see screenshot attached.
You should be able to set the dimension names in the Merger Node configuration ("X,Y,Channel"). Otherwise, use the Set Image Metadata node to set the Label of Dimension 2 to "Channel".