Windows 10 Java edition
This did NOT happen as recently as 19w08a!
I have tested this on an arbitrary track with nothing important around it. No parallel tracks needed, no walls nearby, just any ordinary bend in the track.
Sometimes the cart stops (gets stuck) on the corner, and continues making rolling sounds the entire time until you dismount.
Sometimes it just bounces and turns around making a funny U-turn.
More rarely it slips off the track as though it thought the turn was a block too early.
It happens on flat tracks on corners, and on inclines equally. It looks funny to get stuck on a corner just cresting a hill, and never finish cresting but neither roll backwards back down the hill.
But as of this version, so far as I can tell, absolutely NO minecart can travel through any corner in any direction.
I would be ASTONISHED if this were the first report of this bug, but I cannot find anything exactly like it in all of my searching thus far. Just bugs talking about inclines only, or parallel rails only. So please don't be too upset if this turns out to be a duplicate, I did my best searching.