We recently had one other person with this same question: https://ajarproductions.com/pages/products/in5/answers/7286/rgb-colors-seem-to-be-converting-to-cmyk-in-in5-output
After a restart of Adobe InDesign and downloading the latest version of in5, the issue was resolved. If you are still having an issue after using in5 3.8.2, please let us know here and send over your InDesign file to firstname.lastname@example.org so I can take a look. Thank you.
I did use the latest update but the issue remains.
I have noticed the following issues:
Text colors remain once you keep them editable. If you select pixel perfect the recovering is happening to CMYK.
If you use a logo the same happens only if you import the logo as svg the colors remain correct.
The blue in the square bulb is the correct blue (the headline should be the same blue)
If you remove all imported images then the issue is also solved.