Experiencing a very strange issue with AS, curious if anyone also noticed.

Example 1: SIN-HND-LAX

Segment by Segment
SIN-HND = UNAVAILABLE
HND-LAX = AVAILABLE
SIN-HND-KIX = AVAILABLE
(sin-hnd is all same flight and date)

Multi city search:
SIN-HND-KIX + HND-LAX = AVAILABLE
SIN-HND + HND LAX = UNAVAILABLE

Thinking it is phantom inventory, I booked SIN-HND-KIX + HND-LAX and the booking system TICKETED the reservation lol. So right now I may have to fly this strange itinerary (its fine because it gives me 20 hrs in osaka before i need to get a $100 domestic ticket to HND.

Example 2: LAX to TYO

LAX-HND = UNAVAILABLE
SFO-LAX-HND = AVAILABLE (same tpac flight date and #)

I'm not extremely motivated to book a flight to reposition from LAX to SFO just to fly back to LAX again but I guess I can do that if need be if desparate times comes to desparate measures, but has anyone worked their way around these strange inventory issues?