Put together a simple itinerary in J to show someone the tool:
PER-SYD-SCL-GIG-LHR-SIN-PER
The tools shows the base fare to be AUD23,998

which is exactly double what KVS shows as the ex-Australia DONE4 fare (AUD11,999)
Tried a quick change (start and end in HKG, first flight on CX)
now the tool bombs out with the error message
No fare can be found for the flights and/or cabins you selected. Please search again and select another cabin and/or different flights. (5685 - 2201)
Update 19-Dec
both issues now seem to be fixed
- ex-Aus base fare is now correct
- ex-HKG now working