Beautiful game from the start. So simple but so aesthetic and pleasing. One of my favorite idles I've played.
I also had the bug of maxing out all upgrades but not getting the achievement.
And I also had the bug where they stopped spawning. For me, to cause this bug I had to click "Buy Max" on the spawnrate upgrade when it was already maxed. Clicking all the other "Buy Max" buttons did nothing (even UI), but clicking the spawnrate's "Buy Max" showed the button being pressed, and the pixels stopped spawning.