I'm on 4.8.3 version still, but not sure this would be causing this. I have been unable to save captures to pdf's in full colour for a while, only in grayscale.. I thought I may have tweaked a setting some place, but I can't really find anything. The scanner toolbar options do not suggest much ..
Any help will be gratefully received.
PS. I have thought of restarting SC and colour pdf's are back
Could this be a memory-related thing? Anyway, I'm glad I can use the pdf export again!