My understanding is that Player 1 while running around rolled down the stair behind the Archery Target (see picture) and ended up stuck between the Archery Target and the Fence.

Player 2 was towards the bottom of the screen and walked to far away down - getting teleported back to Player 1.

Neither Player can get out.  Tried having Player 2 exit game and re-enter, but player re-enters at the same coordinates as Player 1 in stuck location and not offset enough to get out.

NOTE: Not sure which version - Could only find version details of 1.01 on PS4.