Invalid location of rocket port extension results in no error

I made a rocket platform and built a rocket.

I added a rocket port extension, one tile HIGHER than it should be.

There was no error and this was my first rocket, so I had no idea.

I added another building, the gas rocket port loader. Connected gas and power. No errors. The system was idle but my gas cargo canister was not being filled.

Turns out I should have built everything one tile lower. There was no indication in the game that I did something wrong.