Had an issue today where menu_block module wasn't showing when clicking a link to a view with argument.
create a view with path 'my-view' and add a node id argument
create a link in a menu to my-view/1?? (or whatever node you want to link to)
create a menu block on the menu where you created the link
clicking the link will not show the menu block
change the view path to my-view/% and all is well
Assume this announces the trail properly to menu_block so it knows we're at that path, where before it had no idea.
So our best practice going forward is to always add /% to the path for views with arguments.