Thank you for the kind words and for catching the bug, I could have swore I had an if guard for that!
Also really good suggestion, added in the new version.
Ah, nice. This change already feels better. There seems to be some weirdness with the new up/down controls, though - sometimes when you try to select a tower that you just moved vertically to, the finger doesn't point to the top tile and it doesn't select. Moving left then right clears this, allowing you to select the tower again.