There are two circumstances where players will reappear at the beginning of the level:
Players who die and leave, and new players who join to replace them are instead spawned at the beginning of the level.
Sometimes dead players are respawned at the very beginning of the level instead of the next checkpoint.
The former occurred during what I believe to be the very beginning of Consignment Yard HL-17-36. A player who died had quit, and the subsequent player that joined to replace them was instead spawned all the way at the mission beginning.
The latter occurred in Excise Vault Spireside-13 right before opening the vault doors to enter the room containing a checkpoint, which is connected to the final event room.
I think a fix was made for the second issue. I’m keeping an eye on the first one trying to figure out what causes it. If you could provide the log for a game where this happened that would be apricated. (How To
Thank you for the report!
To clarify, talking to a friend who was in the match:
Prior to when I opened the double vault doors that lead to the final checkpoint in Excise Vault Spireside-13, he claims to have teleported to the beginning of the level, despite spawning inside of the final event room past the checkpoint initially.
edit: I’m no longer home as of the moment but this may or may not be the right log. I’ll update the post with a second log just in case in about 3 hours.