One play button is not displayed, the other does nothing. Double clicking on the .exe file just opens the Steam Client.
What I already tried:
- Being annoyed

- Googling
- Completely quitting Steam (not just closing the Steam Client) and restarting the Steam Client
- Reinstalling the game on a different drive (reinstalls X3TC and X3AP, too)
- Reinstalling Steam and the game on a different drive
What I would try next:
- Being angry

- yelling profanities

- bashing my head against the wall or on my keyboard

This is what it looks like:

Any help is appreciated!