I have discovered that it is nothing at all whatsoever to do with pimax the fact that it no longer applies changes, it is 100% Nvidias fault, or possibly windows (not tried amd so guess could be windows).
I know this for a fact, because i also have a projector and that no longer saves color changes etc either once i restart the pc or disconnect and connect it, it did before without issue, and because the only way to change the pimax from video mode to pimax mode it essentially to restart it ( it does this itself), it won't save any changes because either the graphics card or windows removes them, NOT the pimax. Pimax cannot fix this because it is not an issue with hardware, it's something in the graphics drivers or system which effects not just pimax but other display devices, such as my projector.
It does not however effect my monitor, which is connected via display port. My projector is dvi to hdmi, and pimax is hdmi, so maybe just effects hdmi devices... i have no idea.
I guess pimax could add more brightness options and a gamma option but that would be a workaround and not a fix to whatever causes devices to forget changes.