I suspect there is a bug in the Intel Fortran compiler (220.127.116.11 20200306).
I found out there has been an unsual warning popping up as, for good practice, I changed my ISO_C_Binding declaration of
USE ISO_C_Binding, ONLY : C_DOUBLE_COMPLEX
USE, INTRINSIC :: ISO_C_Binding, ONLY : C_DOUBLE_COMPLEX
which yielded the following warning
mod_parameters.F90(8): warning #8893: The procedure used from a standard intrinsic module is not a standard intrinsic module procedure. [C_DOUBLE_COMPLEX]
whereas that variable is definitely included in ISO_C_Binding.
Sorry if I can't provide more information, as the warning does not appear with a simple minimal working example, where C_DOUBLE_COMPLEX imported either in a module or directly in the main program. The warning does not appear with gfortran-9 or the NAG compiler with aggressive debug flags.