1 day Cruise stop in Shanghai from Okinawa enroute to Nagasaki-eligible for 144 free transit?

Hello! we are cruising Celebrity who tell us that we need a VISA to enter Shanghai when we arrive in Shanghai for a day (arriving at 6:00 am, departing at 10:00pm) enroute from Okinawa (Shanghai for the day) to Nagasaki.
We are confused as the Cruise Ship tells us we need a VISA and some of the Visa issuers say the same! We have read about the 144 hour free transit and think we should be able to take advantage of this? We are all Canadians.
Thank you in advance for your thoughts about this.
Best regards,

Helen