tMPI error on using mpd deform

GROMACS version: 2021
GROMACS modification: Yes/No

I have a simple POPC membrane which runs well prior to trying to use deform to stretch it.
Only change is to add a line to the pcouple section:
pcoupl = Parrinello-Rahman ;; Berendsen ;
pcoupltype = surface-tension
tau_p = 2.0
ref_p = 1.0 01.0
compressibility = 0 4.5e-5
refcoord_scaling = com
deform = 1 1 0 0 0 0


grompp executes normally with and without the deform statement
mdrun throws an error: tMPI error: Invalid tMPI_Comm (in valid comm)

the cmake I used to compile is straightforward ( cmake 3.20, CUDA 11, gcc 9.3 )
cmake … -DGMX_BUILD_OWN_FFTW=ON -DREGRESSIONTEST_DOWNLOAD=ON -DGMX_GPU=CUDA -DGMX_USE_OPENCL=off

Do I need to recompile with MPI to use deform ( assuming deform is the correct parameter to stretch a membrane ) ?

thanks for any hints.
Paul

Firstly, mdp… deform is the correct parameter to use for strain development.

I am able to get the system to run by not using -ntmpi and -npme when starting a simulation. However without thses specificatons now only one gpu is used . This is likley which i related to the tMPI error.

Is deform somehow restricted to one gpu ?

Paul