My ground keeps falling when starting the game

Even though I have 0 for roll, pitch, and yaw and also I have disabled the gravity for ground, it still keeps falling.

Additionally, I was thinking of grouping the ground and maze together (which I don’t know how) and then make a blueprint for both.

My intention was to rotate the ground every game tick about 0.001. Do I really actually need to group the maze with ground to make it tilt/rotate with the ground?

Also, how should I avoid the ground from keep falling?

Will it seems very weird but when I rebuilt the lighting it started working.