Castep parallel execution error, MS 2021 (V 21.1.1.8)

Hello, we are experiencing unresolvable problems with the latest Materials Studio version on our Linux cluster. Typical error messages that occur look like this: 
Job started on host alcc112 at Mon Jul 19 10:49:11 2021
forrtl: severe (174): SIGSEGV, segmentation fault occurred Image PC Routine Line Source libDFTD.so 0000145FECA4BEF2 for__signal_handl Unknown Unknown libpthread-2.28.s 0000145FECD93DD0 Unknown Unknown Unknown libc-2.28.so 0000145FE9D862A6 strtok_r Unknown Unknown libmpi.so.12 0000145FEB76B991 __I_MPI___intel_s Unknown Unknown libmpi.so.12 0000145FEB625BE5 Unknown Unknown Unknown libmpi.so.12 0000145FEB6288F4 Unknown Unknown Unknown libmpi.so.12 0000145FEB5C964B Unknown Unknown Unknown libmpi.so.12 0000145FEB5B6BDB MPI_Init Unknown Unknown libmpifort.so.12 0000145FEB004240 MPI_INIT Unknown Unknown castepexe.exe 00000000006288A4 comms_mp_comms_in 847 comms.mpi.F90 castepexe.exe 0000000000410193 MAIN__.V 149 castep.f90 castepexe.exe 000000000040AD62 Unknown Unknown Unknown libc-2.28.so 0000145FE9D1F6A3 __libc_start_main Unknown Unknown castepexe.exe 000000000040AC69 Unknown Unknown Unknown .

etc...

Our hardware is: HPE ProLiant DL360 Gen9 (Product ID: 755258-B21) 2 x Intel Xeon E5-2680 v4 @ 2.40GHz, 512GB RAM (16 x 32GB). CentOS V8. Any idea what might go wrong ? The message occurs on any CASTEP parallel run submitted to this node. We have installed *exactly* the recommended hard- and software.