Good to know, I run into the same problem on my Samsung XCover 4S since some months: each time after Navigaton App crashed (doesn't end, just is dropped from the screen into the backgrouund back to the main menu), I used MyrouteApp - as you recommended in your post.
As I (and maybe others) thought, the crash resulted from some Samsung update), wouldn't it be helpful to release an update of the Navigation Up just with a message "App discontinued, use MyrouteApp" for all those that run into the same problem ?