I dont know why, but it some times bugs out. Reset solves it.
Thanks for playing, happy that you enjoyed the game! I had plans for a level select screen, but the time got short and all, sadly I had to focus on more important stuff (that's why the menu only has one button lol)
As for the bug, it seems that a specific order of inputs (placing auto, placing manual, removing, etc) can cause this problem. It's unfortunate that I couldn't fix it properly, but at least you can always reset without losing progress.