For completeness of this thread, I’ll provide the below update:
I’ve decided to work around the issue by having sections for Assignees. I would much prefer to have more meaningful sections and use the filter option to filter by assignee, but because the filter doesn’t work on sub-task assignee, this isn’t possible. The data I did want to group by (i.e. use to define section names) isn’t going to change between task and sub-task and therefore it is possible to use filters to search on this.
I considered have separate projects for every individual, with a parent project with the sub-tasks so I can have a single workload view, but I didn’t see how you could automate the promote to project in sub-tasks. It also feels too high a risk that assigned tasks would be missed.
In a separate thread, about another limitation of sub-tasks, someone helpfully provided the following link:
This video highlights a lot of useful ways you can use sub-tasks, but then reiterates the caveat that you shouldn’t use them (or should significantly limit their scope), if the limitations of sub-tasks are a blocker for you.
I do think it’s very reasonable that the “My Tasks” button, and any filter by assignee, would include sub-tasks as well. It includes milestones. I would hope this gets onto the Asana backlog. However, given I see that this was requested in a forum in 2020 and there was no actual acceptance of the issue, I’m not hopeful.
Here is the other thread I mentioned. I’m hoping to work around the fact that sub-tasks aren’t included in the Power BI export by using the API to export the data from a script.
Allow the Power BI Connector to also pull the Subtaks - English Forum / Product Feedback - Asana Forum