The issue:
In some cases when teleporting a player that's riding an entity that's also being teleported, the player doesn't appear to get teleported.
I'm not sure on the specifics unfortunately. I have only seen this issue happen in a theme park map I'm working on and have not been able to re-create the issue in a test world.

In previous versions of Minecraft (1.19.4 up to 1.21.1) I didn't see this issue.

I have attached 2 videos to show the issue. Both start in VSCode with the datapack from my theme park.

• Video 1 starts by showing the function for resetting the player when exiting a ride. This function is executed as the player.
• I point out the teleport command, which is "tp @s 61 0 42 90 0".
• I also point out a debug command I added, which is "execute positioned 61 0 42 if entity @s[distance=..1] run say < 1" (If the player is less than 1 block from the teleported destination, it will say "< 1" in chat)
• I then switch over to Minecraft, where the ride is about to finish. Notice that I don't get teleported, but in chat it does say "< 1".
• It appears that at least the server thinks I (the player) was within 1 block of that location

Video 2 starts by showing the exact same function, only I added a command that kills the entity I'm on.

• In the video I point this out.
• I then switch over to Minecraft, where the ride is about to finish. Notice that in this video I do get teleported to the location. The behaviour I was expecting originally.

Some more information that I think may be useful:

• The entity I'm on in the videos is an armor stand, although I found that the issue also occurs on other entities (item display).
• This happens with multiple rides in my theme park that teleport players at the end.
• In one case I found that re-arranging the commands helped, but in others the same solution didn't help.