The handle isn't locked in the upright storage position. It requires a specific two-click action.
Fix: Carry the machine using the bin handle. Push the main handle firmly forward until you hear two distinct clicks. The stabilizer wheels will drop down automatically when the handle is locked. If you only hear one click, it's not locked.
If that didn't work: Check for obstructions around the ball or hinge. Ensure the cleaner head is fully attached and clicked into place. A misaligned head can prevent proper balance.
Heads up: Always store the machine with the handle locked upright. This protects the ball mechanism and prevents accidental tipping.