at the bottom of each dashboard app (child) there's a Legacy Link.. use that.
If you modified your dashboards to use the NEW Link Template, you need to revert them back to Dashboard Links template.
THEN, to view a Dashboard, use that Legacy link to get to one of the Dashboards. The Tiles should now work again. I am not sure, but I think the underlying URL changed and if you have a saved shortcut, you may need to update.
