So this was a doozy to figure out how the bug worked, but I finally did it and here is how:
Steps to reproduce:
- Spawn at least two Astronauts side by side and take control of one
- Select the other Astronaut
- Move the info panel out of the way of the pause menu, you'll need to be able to use this menu while the game is paused
- Go into first person while the other Astronaut is still selected
- Pause the game
- Take control of the selected Astronaut
- Notice that the other Astronaut is now invisible, with only a shadow. His hit box is still there, but you cannot see him.
This also happens when you enter and then leave a capsule again whilst being in first person mode. When you switch to 3rd person the astronaut is invisible untill you change to first person and back to 3rd person.