This bug doesn't happen all the time but it happens in like 30% of the time. If you create a small platform in the air and put powered rail all the way untill the platform ends and charge them, after you put a minecart and get on the minecart, start riding and and when the minecart gets boosted by the powered rails, stop moving forward by the letting go of the analog stick . In theory, the minecart should simply fall from the platform because of the boost from powered rails. But this bug makes it so that the minecart gets stuck in the edge of the last powered rail. Even if you try move forward, nothing happens. So the minecart just gets stuck and the only option left is to get out of the minecart. It is so uncomfortable when you are riding a roller coaster. This bug is still in the 1.16.21 update for the nintendo switch and possibly on all the other bedrock platforms as well. Hope this gets fixed.