Typically this happens to pdf files due to Acrobat/Readers default color management, So select File > Print > Advanced and enable the 2 highlighted options below , otherwise it will output as RGB, and adds magenta to all output, which will give grey a purple hue, Blues will be very affected as well.
Then make sure Color Adjustments is on 0 for all
Also make sure that Color correction is not set to do any odd things, try it disabled completely and see if grey is grey.
And if all else fails, try the other options here:
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