There may be a couple of reasons for this:
Turn off the main pool pump while the robot is cleaning.
If the pool pump is on, sometimes the water flow of the pool pump pushes the robotic cable over the robot while it is cleaning. On occasion, the cable will tangle with the robot when the robot is cleaning the walls of the pool.
The robot’s handle needs to be locked diagonally.
Reverse the diagonal direction of the floating handle with each use. This will prevent the cable from tangling.
Do not put the entire cable into the water.
Use only the required amount of cable necessary for the robot to cover the pool. Most robots have more than enough cable.
Remove any additional flotation that may have been installed by you (robot may be climbing the pool too high).