Not saying BaseCamp should crash on import errors but what's wrong with the file you are trying to import?
I haven't got a clue, and to be honest I wouldn't even know where to look plus I'm getting tired of beta testing supposedly stable releases. It happened with three separate waypoint files that I exported from my "Master" library and tried to import into the one I'm currently planning in. These are all Dropbox synced libraries. The first import would work fine but the second one would crash the application. Rebooting would let me import the second but then the app would crash when I tried to import the third. I should note that there seemed to be some cloud data transfer issues going on at the same time. This all happened on my MacBook Air. I've since moved to a different computer and all seems to be working well, for now.
This could be the same issue that Dan is experiencing. It looks like mixed profile routes import is broken in 4.3.4. We found and fixed the issue and it will be in the next release. In the meantime if that is your issue, then unfortunately the only work around is to change the route to use one transportation type before exporting. If that isn't your issue, then please send the GPX file to me. Sorry for the inconvenience.
It appears this could be a device specific or one off problem. I'm currently on the road and don't have access to the computer that caused the problem so I imported the original files to BaseCamp on my travel MacBook Air. No problems. I'll investigate further when I get home.
