Calculix solver breaks/terminates without an error with models larger 250k elements

I investigated more, as some models still do not run and break up with no error.
My observations:

the more cores i use by setting: set OMP_NUM_THREADS AND set OPENBLAS_NUM_THREADS
the more likely a model runs through.
ccx 2.21 with PASTIX breaks up more often than using the i8 compiled ccx 2.18 by rafal.
Changing PASTIX_MIXED_PRECISION=0 or PASTIX_SCHDEULER=1 did not influence the behavior.

My issue is, that my models are all below 500.000 elements,
but I use a lot of different material definitions and contact pairs.

Running the models either without many material definitions (so only with one material for all elements)
or without contact pairs leads to a “solvable model” for any solver.

But with my material and contact definitions, only models below 250.000 elements are solved robustly.

ATM i try to find a combination which works, or alternatively try to set up the Calculix with pardiso OUT-OF-CORE mode

Any other suggestions?
Thank you all!