With Expertflyer, sometimes you'll have to change the POS as well, it defaults to America... not often but sometimes the availability is different. Your POS is "I believe" the country you originate in, but someone will correct me if it's the country of the issuing airline. My current CX RTW ticket was issued by CX's Tokyo office so my POS is Japan either way.

The OW tool for some reason doesn't like CX flights. The only way I could get it to offer them to me was to select CX as my preferred airline in the top right side. That potentially causes other issues, but managed to make it work out in my case.

One other issue you might be experiencing if it's not pricing, sometimes it doesn't want to price out BA and IB long haul segments, see if you can get AY or QR if you have some BA and IB in there and see if that helps. Also sometimes it won't price if you have a segment in Economy or Premium Economy, even though that's certainly allowed if you want it. But like others have said you're definitely allowed to have well over 34,000 miles on a OW Explorer, the design of the website is pretty bad, it should just remove that line entirely after you've exceeded 34k since that'll be a OW Explorer, not Global Explorer. But that's not the reason it's not pricing, it can be ignored entirely.