HK - PVG then Cruise then PVG - HK

Hi there,
I have a British passport and will be flying to Shanghai from Hong Kong on the 22 March and then go straight to a cruise for 7 days (visiting South Korea, Japan, South Korea) and then the cruise ends in Shanghai again on the 29 March.
I plan to stay one night in Shanghai and then fly back to Hong Kong on the 30 March.
I can't seem to find any information on whether this is a permittable route eligible for the 144 Hour free transit, I have spoken to travel agents, visa agents, cruise agents, airlines and no one can give me a straight answer!! Please can you advise?
Thank you.
Thank you!