The Best Landing
Providing the player with new tools or adjusting the game interface, without fundamentally changing gameplay.
Play it your way.
On 2.1.x, selecting the "level 4: Production base" blueprint option appears to overlay the "level 3" base over the top half of the top portion of the "production base" blueprint, leading to missing production buildings.
This issue appears to impact Vulcanus as well, and presumably all other planets.