When I click the link at the top to "Show All Subtasks" it does so immediately for that view, and the link changes to "Hide All Subtasks". However if, say, I add a couple tasks and then refresh that view (required in order to get the newly added tasks into their proper location on the page), the link still says "Hide All Subtasks" as if they are currently showing. Yet after any page/list refresh all subtasks are automatically reset and are not showing. So I must then click the "Hide All Subtasks" link and then immediately click "Show All Subtasks" to get the view back to showing all the subtasks.
This can be easily replicated. Just click "Show All Subtasks" in any view, then perform any action which will refresh the view and the link still says "Hide All Subtasks", requiring two clicks: One to make it say "Show All..." (though the subtasks don't change with that click), and then again to actually show the subtasks.
Of course I have already requested in another thread that the "Show All Subtasks" feature be made a user selectable option to show them all the time. That would hopefully alleviate the problem.