Now this file is extreme: it was terribly low light and I underexposed it two stops (quick way of overriding the max ISO limitation I had set) but I have seen this in some other files too. This is the original:
This is how I chose to process it: (not very successfully!)
The processing involved pushing by 2.2 stops, sharpening of 60/0.7/70/20 and luminance NR of 25, then some heavy extra local NR in the sky.
I noticed some vey weird effects - and crucially I noticed three things:
1) that they disappeared when I turned lens corrections off
2) that they do export to JPEG, so it isn't a LR screen rendering issue
3) the NR makes them better and the sharpening makes them worse, as you'd expect.
SO here are sky crops from a copy of the file WITHOUT any local area adjustments. The first with Lens Corrections ON and the second with them OFF:
And here's what it can also look like, from another similar file with sharpening as above and no NR, underexposed 2 stops but not pushed in post.
No biggie, these files are poorly exposed and quite strongly sharpened but I found it interesting so I thought I'd share. Might be worth turning off lens corrections under any such extreme circumstances...