You'll probably get several people Telling you i'm wrong but if your going to be Using CMYK its best to have the art set in CMYK not RGB. It will alter the look of some of your work (Sometimes). Most of the time you'd probably not notice it but THere are occasions where The RGB and CMYK will look noticeably different on screen. And even Look different When printed from the RGB file and CMYK file. I've came across such problems in the past. You could change them to CMYK and show your client the difference they may not mind. CMYK is best for Print In my opinion.
Perhaps take this online video tutorial, you can get a 10-day free trial:
https://www.lynda.com/InDesign-tutorials/InDesign-Insider-Training-Color-Management/410686 -2.html?srchtrk=index%3a1%0alinktypeid%3a2%0aq%3aInDesign+and+color%0apage%3a1%0as%3arelev ance%0asa%3atrue%0aproducttypeid%3a2
Even though you say the color settings are the same, I would double check to be sure both the file and software are matched in the Color Settings. It's easy enough to manage in Bridge using Edit/Color Settings and ensuring they are synched.
If you don't have Bridge installed, go to Edit/Color Settings in InDesign and Not only check the Setting, but the Conversion Options below. If that is different, it will convert your RGB to CMYK differently per user.
I received an InDesign file (in CMYK color mode) with color swatches created in RGB color mode.
InDesign doesn't have a document color mode, a document can have a mix of RGB, CMYK, Lab, and spot color swatches.
When you edit a swatch and change its Color Mode from RGB to CMYK you get a color managed RGB-to-CMYK conversion of that color. The values you get will depend on the document's assigned color profiles, (not the Color Settings' working color spaces, which could be different).
The resulting CMYK values differ between one computer and another
Just to clarify, are you making the conversion on computer A, saving the file, opening the same file on computer B and seeing new swatch values? Or, are you making two different swatch conversions on computers A & B?
A great mystery so far !
One note on Swatch conversions. When you convert an RGB swatch to CMYK the values should represent to any changes you make in the document's assigned profiles, color intent, or black point compensation before you make the conversion. But I've noticed that the swatches can become "sticky" and the conversions aren't necessarily correctly made into the document's assigned CMYK profile—it seems to remember the document's original assignment. I've always thought it was a bug.
The Toolbar's Color Picker also lets you make color managed conversions and it responds correctly to a change in the document's profile or color intent. If your problem is the swatch stickiness, you can test that by opening the color picker, entering the RGB color, checking the picker's CMYK values for that color and seeing if they are different than the Swatch panel's conversion.
Thank you very much Rob. It's a bug of the swatches panel and your recommendation to check colorpicker values is true. I advise the others who had the kindness to answer me to try it. Thanks all.