What should I do if my robot keeps floating on water and will not sink?

It’s because of the air caught in trapped in the robot. Gently tilt the robot from side to side or turn upside down under water to remove trapped air.

My X11 does this every single time I use it. If I don’t check on it every 20 minutes, it will use up the entire battery just floating on the surface and not cleaning. I am beyond frustrated with this.

Sorry to hear this. But we’d like to get more information to help with this issue.
Is there coping of your pool?
Can you make a video of the whole process including it before floating?