I flew 6 flights today using SD Tablet Android 3.12.6.19363 and backed up logs to the cloud as usual. The logs load Ok on the tablet and on my Android phone. But on PC they appear corrupt. They are ok in the log summary and have all the data I would expect but if I try and open one, they are the bottom of my logs with a date of Jan 0001 and no time data - and when I try to open one of these it comes up with an error "Object reference no set to an instance of an object". Flights logged a few days ago on 2nd May (before I updated to latest release I think) appear OK on my PC. Has the latest Android SD update caused a problem with logs?

You've identified the problem. You need to update your PC software so it understands logs produced by the latest Android software.