Ann: Great Australia Royalty - Update , page-14

Alimak, Lionel is correct that there is a dispute over sulphide vs oxide ore however IMO you are partially correct, they are delaying payment for their own reasons.

EXS already gave them 90 day terms to help them during a problematic start up so they may be just trying to hang onto their cash for as long a possible. Ultimately the company is backed by SOL so they are hardly in a position where they can't pay their bills.