Your screenshot shows that you are proofing CMYK colors in Photoshop, which could explain the different color.
Press Cmd+Y to turn the proof off (or View > Proof colors).
Does that make any difference?
Thanks and well spotted, but unfortunately that hasn't made any difference.
Well, when LR and PS don't display identical colors, it's usually caused by a defective monitor profile, but it's not so common with Macs, more so on Windows.
As a diagnostic tool, and as a possible temporary fix, try setting the monitor profile to sRGB, or Adobe RGB if you have a wide gamut monitor. I'm a Windows user myself, so I can't give you any instructions, but take a look at this article:
If this fixes the problem, you should calibrate the monitor with a hardware calibrator.
Thanks for the advice, however, I have colour parity between all the other images I've checked. It's just this image that is problematic. That would seem to rule out a profile problem as I would expect that to effect all images.
I'll re-calibrate my display though and see if that makes any difference, but I calibrated it on Monday with a ColorMunki Display.
Recalibrated with the ColorMunki and the problem persists.
I'm not familiar with smart objects, may be that somehow has caused the problem.
The file was too large to save as a TIF, so I saved as a PSD
As far as I know, TIF has a maximum file size of 4 GB, which is quite a lot.
What are the pixel dimensions of the image?
Did you edit the image in PS and add layers before importing it to LR, or did you import to LR straight from the camera (or scanner)?
The image is big (11000 x 4000), but is made bigger by the fact it contains an additional image for focus stacking. There aren't actually any smart-objects in there now as I had to Eastertide them so I could merge them. There are also a lot of luminosity masks and adjustment layers.
I didn't import it into Lightroom. I created a panorama from several images in Lightroom and chose 'Open in Photoshop as a smart object'. This opens a PSD containing the image which is automatically added to Lightroom when the file is saved.
In that case I suggest posting in the Photoshop forum, where you might get better help.
Hopefully a moderator will see this, and move the whole thread to the Photoshop forum.