This method is declared in source/processes/electromagnetic/xrays/include/G4Scintillation.hh as void SetScintillationYieldFactor(const G4double yieldfactor); but not implemented. Code using it compiles but linking results in an unresolved external
Thank you for reporting this. It is now fixed for both upcoming Geant4 versions 11.1 and 11.0.patch-01.