I made the same observation (nodes are ok, but no elements), therefore I thought about the bandwidth of the mesh I am giving - and here is the solution to obtain proper partitions:
1. output an optimized input by the commands
OPTI
OUTM
2. partitioning of this flat input file
However, I wonder whether giving the mesh as a separate file may be the problem here. I did not concern this, as the mesh (file "netz") has the same structure as the feap's flat input, but maybe the include-command in the input file is the problem here?