This button has never worked and was never intended. Currently you can set
a downtime on all services and hosts contained in a BI aggregation. But
there is no way - alas - to revert this and remove all those downtimes. The
reason is that for creating a downtime you just need the name of a host and
service. For removing one you need its ID. And that is not available in BI.
To the list of all Werks