@Loyce1 It appears that there may be a discrepancy between how the permitting department and the zoning departments are counting bedrooms. If your local zoning department has you zoned for 4 bedrooms, with the assumption that each bedroom may accommodate 2 persons, then the permitting department should be allowing 8 guests. Unless you also have to reside on the STR property, in which case 6 guests would be accurate as you would be presumed to be utilizing at least one bedroom.
Good luck fighting city hall!
Note: I do not reside in your state or county, so I am generalizing the rules. But I have lived many places and have had many properties over the years, and zoning is usually what wins.