To Reproduce:
- Create a Venture Station and send a ship on a venture.
- Redesign the station, forcing the Venture Modules to be rebuilt, while the ship is still on a venture.
- Station waits for return before deconstructing module <OR> Ship is forced to return <OR> ship is destroyed.
- ship stays on venture and is unable to return for all Eternity.
Here's a picture of my ship being MIA - the one marked won't ever return: https://i.imgur.com/bcswUvw.jpg; as you can see i can send new ships on ventures just fine though.
Ps: I'd assume the same happens, if someone were to blow up the venture module unexpectedly - but I've not tested the latter.