The occupancy field is not used in the the zone calculation expression (could be). The formula used to calculate the number of occupants/zone is: meas area / occupant load. Looking at your image, there is not sufficient info to determine the problem area but I would say that the zone stamp was altered manually to give that result show with a custom field,
You could alter the expression formula to calculate based on the area type but that would require entering addition info - not a difficult process since you only have do it once.
To see what was altered manually -- take a look at the "classifications and properties" field under zone settings. Otherwise just accept the defaults but the zone load still has to be entered manually. -- All this - Assuming your using the US version??
Gerry
Windows 11 - Visual Studio 2022; ArchiCAD 27