To conclude this discussion …
The problem here was that I tried to pass only a (center) piece of an array to Catalyst which is not possible, and which leads to memory issues.
The motivation behind my attempt to do so was that my ranks each have overlapping parts of the overall information due to layers of ghost cells.
The key is to pass all information to Catalyst but to then also mark ghost cells as such so that Catalyst knows how to deal with the overlapping information.
I still don’t know how to mark cells as ghost cells, but that’s another question which I’m asking here.