RichardMH

Maybe post a file and see what we get?

Threshold might be the quickest way do what you want. Or picker in HSL is a bit more fiddly.

Is hardware acceleration on? Edit->Preferences->Performance

Are your graphics drivers up to date?

Are you calibrating your monitor? Its well worthwhile wide a wide gamut monitor.

Have you tried white balance? Or HSL?

Does turning off the tone curve etc in develop persona do it? (In develop assistant).

Might need a screen shot of the layer stack to see what you've done.

Most of the time I throw them out. Usually its reproductions, cheap prints or amateur paintings.

When you reinstall the nvidia drivers do a clean install. Think it's in the custom set-up one.

I have the Benq SW240 monitor and love it. https://www.benq.com/en-au/monitor/photographer/sw240.html I use a gaming PC with lots of RAM and a decent graphics card.

What colour space is your image in AP? Its in the context toolbar above the image.

Is your monitor calibrated?

Might be hardware acceleration misbehaving. If its on try turning it off. Edit->Preferences->Performance.

Have you tried the move tool? Rotate from the Arrange menu.

Apparently that can cause file loading problems.

Are you saving it on a NAS or some other external drive?

Are you using Open or Open Recent? I've had a similar problem with Open Recent but Open still worked.

You can also save the Pixel Selection as a Spare Channel in Channels so its always there.

I recycle frames from the charity shops. Only real outlays are a mat cutter and mat board.

I realised after seeing h_d's post that was mosy likely the problem.

It works OK for me on a PC. 1.10.5.1342

Are you using Open or Open Recent to try and open the file?

I use Photo and print at home on a Canon PRO-300. Its professional quality but only prints up to A3+. Anything bigger is off to a professional printer (who fortunately is 10 minutes down the road so no postage).