GIMP Version: 2.10.28
Operating System: Windows
OS Version: Win 10
GIMP Experience: Intermediate Level

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I loaded 4 stacks of images from Deep Sky Stacker (DSS) for L, R, G and B. After loading them as layers they show up as 32 bit floating point (which is right). When I try to compose them as an RGB image, the Colors->Components...->Compose... dialog is enabled. However when I pull it up and select RGB my choices are just "Mask layer". The layer names are supposed to be in the pulldowns so I can select them. Why are they not there?

The layers are 32 bit gamma floating point, the image mode is grayscale. What am I doing wrong?

I can kludge around it by converting the images to their individual RGB colors but this is supposed to be the proper workflow.

Can't reproduce the problem. LRGB? What color model is that for? For 4 layers there is only RGBA and CMYK

LRGB, short for Luminance, Red, Green and Blue, is a photographic technique used in amateur astronomy for producing good quality color photographs by combining a high-quality black-and-white image with a lower-quality color image. https://en.wikipedia.org/wiki/LRGB

There is some interesting posts over there on how to do it https://www.cloudynights.com/topic/5755 ... b-imaging/

BEFORE doing "Compose..." right click on each layer >> Layer to image size, or go to Layer >> Layer to image size, for EACH layer, then you should be able to see your layers instead of the mask, or crop the image to have ALL Layers the same size as image (if you move 1 layer before doing "Compose..." you WILL NEED to RE-DO "Layer to image size")
I agree it's not written in there https://docs.gimp.org/2.10/en/plug-in-compose.html that all (visible) layers should be the same size or as image/canvas