Hi there,
I did post a similar message on the Facebook group, but thought I’d post it here too.
I’ve noticed with some images, particularly those with a lot of sky - or similar, that I get some ‘wacky colours’.
I noticed similar issues on sometimes unexposed images too, but this is to be expected.
In the previous versions of NLP I could use the ‘sync scene’ from another, well rounded image and it would work wonders.
No such luck with V3 as it doesn’t have the option (unless I’m missing it).
There is a chance I’m being criminally stupid - I haven’t scanned much in the past year so not really used the app and played around.
I will try to post some examples tomorrow
Any help or advice is greatly appreciated!
NLP v3
Vuescan DNGs with a plustek 8200i
This seems to be fairly in line with what NLP can do. NLP adjusts tone curves according to what it finds in the image. Images with limited structure, contrast and hue content tend to raise the risk of wacky colours. Sometimes, it helps to crop the uniform parts off before using NLP. After the conversion, the crop can be switched off again.
In Lightroom you can mask the wacky areas and adjust the colour to taste, localized to the mask. Just remember that the controls work in reverse on non-rendered raw files.
Thanks, I did indeed try this but it only works for limited scenes in my experience.
Or rather, for some of the images I take, it doesn’t work.
I noticed on another post, it was mentioned about adjusting the black point - this has helped in some cases for me, but isn’t perfect sadly
Yes this is true, I have made Lightroom setting changes, but as soon as I use ctrl-n to load up NLP, it reverts my changes.
@nate is there any chance of bringing the sync scene option back? 
Yes, that would be most welcome 
“…as soon as I use ctrl-n to load up NLP, it reverts my changes.”
That is weird - never seen it happen, nor do I know of any settings in Lr or NLP that would cause it - perhaps Nate has insight into it - he knows the programs from the inside.
Going back to your issue of 'wacky colours", I have not experienced this either, but I am not using either Vuescan or a Plustek scanner. I wouldn’t rule out issues specific to that set-up causing it, either because of how they perform or how you are using them. Needs more info on settings and diagnosis of the scanning conditions.