Hi Marjan —
The root cause looks similar to the previous error you had posted (which I don't think we had ever solved) related to Congestion at the destination endpoint. Did you have CHPL_COMM_DEBUG=1 set in your environment before compiling this program?
The mention of Microsoft.NETCore.App makes me realize: Are you running this from a Windows system? Are the nodes themselves WIndows systems as well? And in either case are you running this from Cygwin or using Microsoft's Bash Shell / Linux Subsystem?
Thanks,
-Brad