Ligue 1 side Nantes President Waldemar Kita is currently holding up the transfer of his 24-year-old captain Valentin Rongier to Marseille.
20 Minutes, La Provence and Canal Plus all report that a €15m fee is agreed, but the two clubs cannot find an arrangement for the sell-on fee percentage clause.
OM are offering 30%, Nantes insist on receiving 50%, their reasoning being because they have dropped their asking price by €5m in order for the deal to be able to happen.
Talks continue, but Kita is in no rush.
This deal could in theory be completed after the transfer deadline, as Ligue 1 clubs can do deals with each other during the Joker transfer window, which runs from tomorrow until December and allows French sides to do one transfer or loan with another French club during that time.