The motor that rotates the head isn’t functioning properly.
Common causes:
Caked-on debris either inside or outside the riser
Rotor motor failure (can’t reach position)
Try this first:
Remove the nozzle & filter.
Re-calibrate the head to let water bubble through it. Note that this will prompt an error as water is flowing through the head abnormally but this is expected.
Re-assemble the head.
Test the head with another quick run.
If the issue continues, open a service case.