Not sure if this is a bug, but I played this game a couple of days ago. When I came back, the progress tab saved my level progress, but I was back to the beginning in the Idle Gradient Tab (1 Pixel Point, 4x4 grid).
Currently progress only saves the size of the grid and the goals unlocked. In a future update I'll try and include it to save the colors as well, thanks for taking a look!
