Whenever you are trying to evaluate pricing rules on ITA, always turn inventory off. The valid connections HND-GMP on all of KE, OZ, and NH show as correctly pricing using UKX8WNMD on that date with inventory off.
As may be obvious if you look at inventory, not all carriers use the same inventory classes: U class on DL is not the same thing as U class on NH, and UKX8WNMD does not use U class on NH. This is the purpose of the third "C" button in ExpertFlyer:
For example, this fare requires K class on NH:
Code:
>$LB1/NH
001 ATLSEL 06DEC23 DL USD 1170.00 UKX8WNMD STAY-||/-- BK-U
FARE CLS EXPLANATION BOOK CODES
-------- ---------------------- ----------
UKX8WNMD NO ADDITIONAL FCL TEXT DATA FOUND U
BOOKING CODE EXCEPTIONS FOR CARRIER: NH
VIA NH NO BOOKING CODE DATA EXISTS FLTS
5001-9999
VIA NH NO BOOKING CODE DATA EXISTS FLTS
2210-3200
VIA NH NO BOOKING CODE DATA EXISTS FLTS
3610-4840
IF VIA DL ALL ECONOMY CABIN
VIA NH K REQUIRED WITHIN JAPAN
IF VIA DL U- FARES
VIA NH K REQUIRED WHEN AVAILABLE BETWEEN TYO-SIN
IF VIA DL U- FARES
VIA NH L REQUIRED BETWEEN TYO-SIN
IF VIA DL ALL ECONOMY CABIN
VIA NH K REQUIRED BETWEEN TYO-SIN
IF VIA DL ALL ECONOMY CABIN
VIA NH K REQUIRED ALL INTERNATIONAL SECTORS
IF VIA DL
VIA NH NO BOOKING CODE DATA EXISTS
IF VIA EY ALL INTERNATIONAL SECTORS
VIA NH K/W REQUIRED WITHIN JAPAN
IF VIA ** ALL CARRIERS EXCEPT NH
IF VIA ** ALL CARRIERS EXCEPT NH
Via OZ it requires V class, and via KE it requires T class. These classes are not available on ATL-HND-GMP for your dates.