There seems to be a bug with the Tier 2 Science Ship.
When I bought it, I can't assign any of my crew members on the Bridge, but I can assign them elsewhere though (Tactical, Culture, etc.). However, I bought the Tier 2 Generalist and it works just fine. Haven't checked if this bug also happens on the Tier 2 Attack Ship.
Sorry I couldn't provide a screenshot, I only have one save file. I'll try to afford it and take the screenshot then.
EDIT: There's also another bug where crew assignments can't be worked on and it keeps increasing everytime I click on it. Link:
https://imgur.com/a/VN3Ps8T