maybe some tips is that, if you want to see the execution of the sub workflow, always use the button view sub-execution so it will bring you to the right execution of the subworkflow
and make sure there are no typos between the field name on the parent and on the sub
maybe one is using playlistId (with capital i) and one is playlistId (using small case L) who knows : v
I appreciate the responses! Thank you so much. I think my mistake was the following:
I was looking at my workflow and sub-workflow in two separate windows. When I just ran the sub-workflow I would receive the ‘null’ error. I realized that clicking the ‘view sub execution’ from the parent workflow takes me to an instance of the sub-workflow where it does receive and does receive the correct output.