recompose after decompose (with edits)

[hat trick]

Using Gimp 2.10 (April 2021).

I successfully decomposed a jpeg to RBG, adjusted one of the 3 layers (and neither of the 2 channels), then requested 'recompose'. The resulting jpg has no color.

Suggestions?

[rich2005]

Are you looking at the correct image ?
You decompose to either greyscale images or image with greyscale layers.
You modify one of the images (or layer)
You recompose and the changes are imposed on the original image.
The decomposed images or image with layers remain.

This quick example: https://i.imgur.com/gIeuy3V.mp4 If you get a different result, please post more details of your image and edit.