i think i had it before.

if i'm not mistaken, you haven't develop the technology necessary to build on arid tiles, that's why your arid tile is highlighted (well... barely) in yellow instead of green.

When you try to build something, i think the game goes with something along the lines: "is the selected tile available for building? yes => build, no => select the first next available tile and build on it"

In galciv2 it didn't happened because the list of available buildings was filtered according to the selected tile, ie on a tile needing terraforming, you could only see the terraforming "building".

Hope this help!

Also, I am under the impression that some of this is in the code that is being developed, that some parts of it are not yet available to us. I would certainly expect the final code to give an error message if we tried to build something on a yellow tile that we didn't have the tech researched yet that would allow us to build there.