Colin,
I have now tried this at least 10 times and each time doing the sequence: print to pdf, close file and choose save when asked, causes Layout to crash. More crash reports: 10034, 10035, 10036 and 10037. Although I would assume each will yield the same information. Its there if you or @adam would like to look.
The Layout file I have been using is 47 pages. When I tried a smaller file, no crash resulted.
Also, with the long file, 10 times with a manual save after the print, then a file->close had no crash. This is the best approach, and one I will use going forward to avoid a crash.
With regard to the screenshot showing the Layout styles which were not synced to the viewports anymore, that may have been a result of relinking the SketchUp reference file rather then a corrupted file from the Layout crash. I observed several times where relinking caused Layout styles to unexpectantly change in stacked viewports. There is a newer post on that subject here https://forums.sketchup.com/t/layout-viewport-style-changing-unexpectedly/156994
which would be the appropriate place for me to provide details.