Happened to be assisting a ProRender User at AMD ProRender Forum because his GPU card and another User suddenly stopped working with ProRender.
DAVID_S inquired with the developers and was told that all R9 Series AMD GPU cards are not supported anymore by ProRender.
Here is the thread concerning this new development concerning R9 Series GPU cards and ProRender: AGAIN - PRORENDER DOESN'T RECOGNIZE GRAPHIC CARD>!>! any help?
EDIT: Here is the official answer concerning the R9 compatibility in ProRender which was just posted a minute ago:
First I would like to sincerely apologize to DAVID_S. plus AMD Manager of Radeon ProRender has clarified exactly what R9 GPU cards are not compatible: