This has been happening to me since X5, so I thought I would mention it again.
Others seem to be having similar colour problems.
You would think that the Default palette would be the Go To for all requests for colour within the program?!
Does anybody else see this?
Tools / Color managements / Default settings / . Change "spot color definition" to any another, like "RGB values" or "Lab values". Then restart corel. After restart change it back to "CMYK values". And restart again. It was help for me. x7 64bit. Windows 7 ultimate.