Fast user switching affects color profile
Thanks for this very detailed post.  I have the same issue, and only a workaround, not a solution.

Workaround consists in going into monitor prefs, change screen resolution to a lower res, then get back to "optimal screen res", and then you original color profile is available for selection.

A bit tedious, but once done, I can fast-switch back and forth and the color setting will remain intact (until I leave either session).

Hope this helps.