While I’m not 100% sure why this result is occurring, one thing you can always try is using the Render Selection feature to re-render only a portion of the image using the desired color prompt. In this example post the feature is used to add orange to a portion of the rendering, which seems similar to what you are trying to achieve.
I haven’t tried it, but you could also try using parenthesis to emphasize the color-object pairing in your prompt and see if that helps. For example, you could try “((green suede chairs)) in a modern office lobby with a (turquoise wall)”. There’s a lot more information on promps in this prompting glossary post too, which could give you some ideas.
Thanks,