Affects Version/s: 126.96.36.199
Fix Version/s: 188.8.131.52
Apologies in advance for the TLDR description.
When in a minecart, you can use the left trigger (xbox controller) to enter another minecart. This is the basis for simple minecart elevators where, for example, minecarts are in a 1 x 1 shaft supported by trapdoors or ladders, etc., and you enter the minecart above from within the minecart below (see, e.g., Monkeyfarm's tutorial https://youtu.be/qShSeP5q6zs).
What I expect to happen is just what I've described, you use left trigger on the minecart above you and enter that minecart, then repeat the process moving up several blocks at a time until you reach the top of your minecart elevator.
What actually happens is that sometimes it works as expected, but sometimes it teleports you to the next minecart's location, but doesn't actually put you into the minecart, and you fall back down (at least in the case of the minecart elevator). In a sense, some of the minecarts just "drop" you.
There doesn't appear to be any discernible pattern to which minecarts will "drop" you. It also doesn't appear to matter at what speed you attempt to go up. Fast or slow, some minecarts will still simply "drop" you.
You can recreate this behavior by building a minecart elevator, and trying to go up one minecart at a time to the top. You can also recreate this behavior horizontally by placing minecarts on the ground a few blocks apart and using left trigger to move from one to the next. It does not appear to matter whether they are on rails or loose on the block. You will move along consistently through a few, and then you'll be standing outside the cart you just teleported to on a few others. I also recommend varying the color of the blocks you're placing the minecarts on, to try to detect which ones you are able to enter and which ones you are not.
Submitted without attachments. Thank you.