Hey @Adam_Fowler,
Thanks for the feedback. Definitely understand the frustration here.
Though not obvious, it is possible to view subtasks in a calendar view. You’ll need to do this through advanced search, though.
Click into the search bar > select advanced search > type in the name of your project > click add filter > select subtasks > search > favorite and rename the search so that it appears in your left hand sidebar.
Hope this helps!