Roughly 10-20% of the time when I enter a nether portal, the game freezes (usually it freezes on the loading screen, though sometimes it freezes before the loading screen comes up).  I have to close the program and restart it (I receive a "closed due to error" message in the Switch menu).  Usually upon reloading, the game has reverted to a prior autosave, but occasionally it restarts to the dead player screen, with the death message that I have fallen out of the world.  In the latter case, the "respawn" button usually doesn't do anything and I have to again close the game and restart it in order to successfully respawn.

I had the same issue in 1.9, though it seems to occur less frequently in 1.10.