The language in TIMATIC has been refined over the years. Previous one had to “trick” it by selecting China as a transit point in order for any of the TWOV language to appear.
Currently, it shows up if China is selected as a destination and gives no reference the stay is a “transit”, “stopover”, or any term along those lines, only the length of stay, and travel to a third country. If the stay is at one of these locations, for less than a period of time, and the passenger has a confirmed air, cruise, or train ticket to a third country, you are good to go.
The following are exempt from holding a visa:
Nationals of USA holding confirmed onward air, cruise or train tickets to a third country, arriving in and departing from any one of the following locations: Beijing (PEK), Tianjin (TSN), Shijiazhuang (SJW), Beijing West Railway Station, Tianjin International Cruise Home Port or Qinhuangdao Sea Port for a maximum of 144 hours, starting from 00:01 on the day following the day of entry. They must have a passport valid for a minimum of 3 months from the arrival date
There is no excuse anymore to screw this up.