Menu item linked to <front> doesn't know its active

I have a menu item linked to and whilst all the other menu items around it take the class 'expanded' or 'active-trail' when they are active, the one linked to does not.

The menu looks like this:

home
sub-page1
sub-page2
page1
sub-page3
sub-page4
page2
sub-page5
sub-page6

When page1 or page2 are active they inherit the 'expanded' class. Which is correct behaviour.

When any sub-pages of page1 or page2 are active, page1 or page2 inherit the 'expanded' and 'active-trail' classes. Which is correct behaviour.

When Home is active it does not inherit the 'expanded' class. Which is incorrect behaviour.

When any sub-pages of Home are active, Home does not inherit the 'expanded' or 'active-trail' class. Which is incorrect behaviour.

Any suggestions?