I have also found the multi-city booking function less useful in the last couple of weeks, particularly trying to get D or I business save fares originating in Asia but not Hong Kong (no stopover on outbound so transit in Hong Kong, but can stopover on return leg). A few weeks ago, there was much availability and prices would be same as simple return - now most prices are coming up at multiples of the simple return fare.

I am hoping it's a temporary system glitch - I haven't tried getting better fare information from a travel agent or MPC, since I have been checking fares generally rather than looking to make a hard booking.

I noted the observation about trip length of less than 7 days. Fares for less than 7 days come out significantly higher. I don't know if fare rules have changed or if CX is actively discouraging ex-HKG activity. If they are, I will be dropping down the tiers fast.