Format or behaviour of @AssetQueues

As per the docs, we have set

‘a list of names of queues whose tickets should always display the
“Assets” box. This is useful for queues which deal primarily with assets,
as it provides a ready box to link an asset to the ticket, even when
the ticket has no related assets yet.’

Set ( @AssetQueues, (‘Cluster Admin Tracking’, ‘PC Admin Tracking’) );

And a widget appears titled “Assets” - but no list or any other content appears inside it:


This is version 4.4.4. I don’t see anything in the (web) queue config interface about further changes needed to specify this showing up. Unsure what’s gone wrong.