How to detect why Ansible playbook hangs during execution

Some of tasks I wrote start and never end. Ansible does not provide any errors or logs that would explain this, even with -vvvv option. Playbook just hangs and passing hours doesn't change anything.

When I try to run my tasks manually (by entering commands via SSH) everything is fine.

Example task that hangs:

- name: apt upgrade  shell: apt-get upgrade

Is there any way to see stdout and stderr ? I tried:

- name: apt upgrade  shell: apt-get upgrade  register: hello- debug: msg="{{ hello.stdout }}"- debug: msg="{{ hello.stderr }}"

but nothing changed.

I do have required permissions and I pass correct sudo password - other tasks that require sudo execute correctly.