Thank you @Kombajn zbożowy for testing the code in airflow 2.10.5
I have since upgraded from 2.10.3 --> 2.10.5 and get the desired task outputs. This issue is probably the one highlighted on github here.
Despite attempts using version 2.10.3 to ensure trigger_rule='all_success' in the @task decorator args this bug was only fixed with upgrading.