There is a known 10.12 issue with open street maps and BirdsEye imagery on BC 4.6.3 that is causing out-of-memory crashes. We have submitted a bug report to Apple, but have no estimate as to when the issue will be resolved.
If you use Birdseye imagery or some OSMs, then you may want to monitor BaseCamp memory consumption in Activity Monitor and periodically restart the app when you see memory approaching 3GB to avoid crashing. Zooming and panning with OSM and Birdseye generally result with memory growing until the app crashes.
Status updates will be posted to this thread.