The drop down menu ribbon commands "Command Tasks" and "Key Sequence Tasks" will only show tasks which are marked as "Favorite". We have received reports from users where the "Favorite" flag was lost and reset to a standard task. In this case, the tasks will then not show up in the menu and the Command Tasks option in the context menu may be grayed out (disabled).

We are still investigating the issue as we are not able to repro it on our side. 

As a workaround you can locate the task(s) and make sure they are marked as Favorite:

Right-clicking an item in the Navigation tree allows you to mark/unmark an object as Favorite.