I am having the same issue with this latest version of LR. I watched your latest video on working around this bug but it is really irritating - like soft proofing by guessing. Tried to find a way to email Adobe directly but no luck. Any ideas about whether Adobe will fix this issue or not?
I'm using soft proofing with Red River polar metallic paper, and simulate paper and ink DOES make a difference on my Windows 10 display. I cannot simulate the anomaly you are experiencing. I am using Lightroom Classic CC 7.4.
The problem is caused by two things:
1. The GPU option as I described above.
2. Turning on the Gamut Warnings (top left and right of the histogram). When you have these on the soft proofing stops working.
It's the same problem in the latest version.
Well, I can't respond to the GPU option. My computer is so old/basic that Lightroom disables the GPU automatically. Can't do anything about it. As far as the gamut warning is concerned, I can activate it and the simulate ink and paper still works.
I can't say why it works for you but I have tried it on two PC's here running Windows 10 and also 2 Mac running High Sierra (I didn't bother testing the others). The latest version of Lightroom Classic CC (7.4) still doesn't work properly for Soft Proofing with the same problem described above and also demonstrated on You Tube (which I think is what janetw was referring to.
If it works for some people but not others then its a bug.
I can confirm the issue on my Windows 7 system using LR 7.4 when:
1. The Preferences> Performance 'Use Graphics Processor is checked.
2. The Gamut Warning (top left of the histogram) is selected.
When either is unselected Soft Proof 'Simulate Paper & Ink' works properly.
Please report this as a 'Problem' at the Photoshop Family forum and place the link to your report in a reply here. This will allow others who land here with the same issue to add their 'Me To' vote. Thank you!
It is a bit daft to buy a state of the art machine (iMac) so it has a graphic processor to keep up with the demands of software like Adobe and then to have to switch it off so soft proofing works. Just not acceptable. Wondering if someone from Adobe reads these discussions!
The other option (switch off destination gamut warning) does work but then it is a pain to keep switching it back on to see if the colours have come into gamut. Again, I hope someone from Adobe reads these discussions. I guess I'll slow down on printing for as long as I can and hopefully this bug will get fixed. Thanks to you, Robin< at least I have a workaround when I desperately need to print. Thanks.
Wondering if someone from Adobe reads these discussions!
Adobe staff rarely read or reply to posts in these user-to-user forums. The best way to get Adobe's attention is to follow my suggestion in reply #6 above and post a problem report at the Photoshop Family Community site.
FYI- LR soft proof has been broken and then fixed numerous times over the various versions. PS soft proof has similar issues as well when using the GPU with anything other than 'Basic' Drawing Mode.