If the RPC worker is not blocked, can you get the output of `kamctl trap`? It is written in a text file, path being printed at the end of command execution.
Is the Ubuntu 16.04 with latest security fixes? Iirc, on another deployment I had access to, it somehow messed up the use of libssl, because it ships normally with libssl 1.0, but I think libmysqlclient-dev enforced the installation of libssl 1.1.