I have tested this 3 times to confirm that minecarts on the game refuse to take corners. To execute the issue, place a rail on a turn of any angle. Place a minecart and push it. As said, you can see the rail doesn't make the corner, rather it comes off the rail or twitches but doesn't make the corner. I made sure to check that there was an issue already made but I have not double checked. Thanks for your time!