Lightroom Classic: Noise reduction effect not displayed in Develop mode

In addition. When press before/after button and copy 'after' settings to 'before' - 'before' image displayed with noise reduction, 'after' image without.

That's not new. LR doesn't display noise reduction or sharpening results except at 1:1 or above. They're still there, and will export correctly. But they aren't rendered at less than 1:1. After they are exported they are "baked in" and visible at any size.

It's always been that way. There's even a little ! mark in the Detail tab which explains the issue...

I think this is a new issue with LRCCC I have this same issue. All my old files(pre LRCCC) show noise reduction at "fit". Any new file i import doesn't show noise reduction in develop module.

I found a sign '!' with an explanation, but it worked well in LRCC before upgrade to Classic without zoom to 1:1. Is there a way to configure Classic do same?

UPDATE: If i have noise reduction at 100%, with the size set to "fit" and White Balance at "auto" the noise reduction effect shows up in "fit" size.

Basically it seems to be linked with the white balance.
If WB is "auto" NR shows in "fit".
If WB is anything other than "auto" NR doesnt show in "fit"

Looks like a glitch to me...or maybe noise reduction is linked with camera WB. Anyone else seeing this?

Also, all my already edited files show NR at "fit"

Same problem here, no NR is displayed at all in my standard "fit" view but is applied when i zoom in.  Unlike the above my white balance has no effect on this.
This is a different behaviour from LR6 and CC which did update NR on the "fit" view quite happily.
Confirmed this by running LR6 with the same catalogue and image.

Its a fairly serious bug as i really cant tell whats happening to my image when making changes if the whole thing appears with noise.

Sorry, but no matter what you see or imagine, noise reduction is only accurate and visible at 1:1 view. What you're seeing when you fit is simply an approximation of some sort. If you need to see exactly what you're NR looks like, then either zoom 1:1 or use the preview window in the Details tab.

Here are some pics. Hopefully the differences are visible on the screenshots
 
Image 1: NR-0 and WB-auto


Image 2: NR-100 and WB-auto


Image 3: NR-0 and WB-As Shot


Image 4: NR-100 and WB-As Shot

Ive found a non ideal workaround.  I've disabled the "Use GPU" in the menu and restarted lightroom.  Without using GPU acceleration normal behaviour is restored, it renders NR and Sharpening in fit and fill views.  Re-enabling GPU functions and it stops again.
FWIW im on Windows 10 autumn update, GeForce 1060 with latest drivers.

Maybe someone else experiencing this issue can test with and without GPU acceleration and a LR restart.

OK im seeing the GPU thing as well. So it must be a driver compatibility issue with the new LRCCC. Im using a GTX titan

It's good to see that I'm not the only one having this bug. I have a GTX 850m and the bug disappears when I turn the GPU acceleration off. I hope Adobe adresses this issue ASAP, because I really feel a drop in performance when I'm not using hardware acceleration... And it's pretty clear that this is not a graphics card driver issue, since there was no bug when using the older versions of Lighroom.

The issue seems to happen with files I edit after updating to LRCCC. Meaning my older files, which I have already edited dont have this issue. Its only on files I havent edited before. Looks like a driver issue to me...or driver-lightroom compatibility issue.

Disabling GPU acceleration solve the problem for me (GT650m). Not sure about performance changes. My files already edited in LR6 have this issue, but think I'm did't exported they before. 
Trying to update macOS for latest version and test.

FWIW ive since tried 3 different drivers ranging from this months latest release to ones for March.  The issue is present on all on them in LR classic.  The issue is NOT present on old Lightroom CC/6 using any of those drivers.
So im going for a bug in LR Classic itself as opposed to a driver issue as all of them worked perfectly on older versions of lightroom.
"Old" video card is rubbish as well, people are getting this with 1050/60/70/Titan range modern high end cards - there are no newer ones!

What OS are people experiencing this on?  Im using windows 10 (autumn creators update) and it does it.  It is doing it for apple users or win7 users as well?