The question was answered in the beta forum.
If your profile doesn't match the color mode, and isn't an output device profile - then it wouldn't be listed because it doesn't apply to that device.
Thanks for the reply Chris, but I'm not sure it was answered... at least not in the topic I linked to – it ended with a request from you for a link to a problematic profile.
The ColorSync Utility states that the profile I'm using is of the Class: Output and Space: RGB, which is identical to the other profiles that are showing up. My printers are RGB printers. Is that what you mean by the "mode"?
>> If your profile doesn't match the color mode, and isn't an output device profile...
You mean OR isn't an output device profile.
Which is a horrible change for print to file operations for some drivers.