Along with Rashford, Garcia, Roony Bardghji and Wojciech Szczesny, Gerard Martin is also unregistered as Barcelona seek to defend their La Liga title.
Martin, 23, recently renewed his contract with Barcelona and has now been promoted from the reserves to Flick’s first team.
Barcelona are now doing their utmost to sell players in order to register their new signings, with Inaki Pena and Oriol Romeu set to leave.
According to a report from Mundo Deportivo, the club are under increased pressure to complete all registrations ahead of the season start.
Their La Liga opener against Mallorca on August 16th could now see the likes of Rashford and Garcia miss out on a place in the squad.