Ohh that would explain why sometimes (I think it only happened with the first tower of each type?) I’d buy the tower but would not be able to place it somewhere else, and it would end up on the bottom of the map, above the bar where you purchase/build towers. I thought it was me fat-fingering the screen and not dragging the tower properly haha, but it’s good to know it wasn’t just me. Still, it was a minor thing and with the generous resources you get I was still able to build plenty of towers where I wanted them.
All in all the mobile support felt like it was very intentional (even if less tested as you mention) and felt as a great way to experience the game.