I have built an RTW itinerary which I believe ends up as a DONE3 OneWorld Explorer, I get this message on the 'Choose Cities' page

Estimated Segments: 13 (max 16), Stopovers: 12 (min 2, max 15), Miles: 34529, (max 34000) , Itinerary Status: Valid

and when I move on to the 'Select Flights' page I end up with 15 Segments and I successfully select all the flights. The Miles: 34529, (max 34000) part of the message doesn't seem to be an issue.

However when I try to add in an extra leg as in HKG-BKK-DOH becomes HKG-KUL-SIN-DOH on the 'Choose Cities' page I get

Estimated Segments: 14 (max 16), Stopovers: 13 (min 2, max 15), Miles: 34703, (max 34000) , Itinerary Status: Valid

and when I move on to the 'Select Flights' page red banners keep popping up saying 'Error Your itinerary exceeds the 34,000 mile limit on a Business or First class booking. To finalise your itinerary, please reduce the length of your trip'. I can still select flights and I work my way through it all but I never get to the end, a 'Review Flights' button.

I am trying to turn this
OSL-LHR-MAD-LAX-JFK-AUS-MIA-SLC-DFW-JFK-HND-HKG-BKK-DOH-LHR-OSL

into this
OSL-LHR-MAD-LAX-JFK-AUS-MIA-SLC-DFW-JFK-HND-HKG-KUL-SIN-DOH-LHR-OSL

I'm now getting message to say that there are no flights from OSL-MAD which I am taking as an indication to take a break and start again - probably tomorrow!!