You need to either use something like MAKE/OPTIONS/Makefile.kokkos_cuda_mpich where you set:
CC = mpicxx -cxx=$(KOKKOS_ABSOLUTE_PATH)/config/nvcc_wrapper
LINK = mpicxx -cxx=$(KOKKOS_ABSOLUTE_PATH)/config/nvcc_wrapper
or you need to set this
CC = $(KOKKOS_ABSOLUTE_PATH)/config/nvcc_wrapper
LINK = $(KOKKOS_ABSOLUTE_PATH)/config/nvcc_wrapper
but then set the MPI library explicitly in MPI_INC and MPI_LIB since your aren’t using the mpicxx wrapper. Also be sure that the scripts in /lib/kokkos/config have execute permissions.
Stan