Why do you expect that? In a color managed environment the document that was converted to the output profile, will be 'reconverted' to your display profile! Only when you soft-proof, with some assumptions for e.g. paper white, you will get something that 'somewhat' resembles the output.
Because it can only do that document profile to display profile conversion, using a specific rendering intent. And, in Color Settings, I'm telling Photoshop to use a default of Absolute Colorimetric. But, displaying appears to be hard coded with an intent and ignore that setting. If they don't want for displaying to use the given default intent, there should be "display intent" setting. It shouldn't be hard coded.
But, I found I can force it to act how I want it to by having the document in the output profile, and converting it back
to ProPhoto RGB using absolute.
Use soft proofing with the same profile you used while converting the document, and turn on paper white simulation.
A better, more accurate solution is to create multiple calibrations to multiple wtpt's, that will mimic the wtpt of the paper in a target environment - you can do achieve it with NEC P/PA, Spectraview II or Multiprofiler software.
I'll admit I hadn't tried soft proofing with the same profile the document is already in. I improperly assumed that wouldn't do anything. And, yes, an even better monitor and color management software is on the list.
And if it didn’t show RGB(255,255,255), wouldn’t you expect the printer to try putting down an off white ink mix? (It would certain solve some gloss differential problems.)
I wouldn't expect that. If the document is in the output profile and has RGB 255/255/255, printing it without further color management sends the RGB 255/255/255 values to the printer, leaving bare canvas white. When the info panel is showing me RGB 255/255/255 is LAB 97/0/2 (because I have absolute intent as default in Color Settings, and that's the LAB whitepoint of the output profile I'm using), I'd like it to display LAB 97/0/2 on the display.