Morning! I find it depends on how you search. looking at UUA then it wont show, if one of the legs has no WTP cabin or availability , so cant offer you that plus UUA. If you search directly for reward flights in CW spending only avios then there were CW reward flight available. Again, Im not an expert on UUA but perhaps its worth a call to BAEC as there could be a way to do it (even maybe flying into DXB and out of AUH or vice versa , again BAEC could help you on this)
There are definitely reward flights of various combinations flying around. In my experience searching only for UUA seems to limit what shows.