This has been an issue for years with the language in the rules. The current rule reads:
(e) Only one intercontinental departure and one intercontinental arrival permitted in each continent except as follows:
1. Two permitted in North America.
2. Two permitted in Asia when one is for travel between the Southwest Pacific and Europe/Middle East.
3 Two permitted in Europe/Middle East for travel to/from/via Africa. If travel is to/from Europe in both directions, itinerary may not include Mauritius/South Africa.
Formerly, rule (2) required that the Europe < > SW Pacific entry/exit of Asia was not to involve a stopover (i.e. 24+ hours) which would have made your itinerary "legal" only if the first HKG stop was just to change planes. The stopover language has now been removed, so it appears "legal," but I suspect you've encountered an agent that's unaware of this subtle change. As in all such instances, the solution is to call again, armed with the rules in front of you.