DocumentTree 'openTo' not working at level 2 of a tree

I have a case where the openTo parameter seems to work for level 1 and when clicking on a page at level 2 nothing happens and the tree stays closed.

Here is the code used in a panel page:

{{velocity}}
#panelheader("Tree")

{{documentTree root="document:xwiki:Doc.WebHome" openTo="document:xwiki:${doc}" compact="true" showAttachments="false" /}}

#panelfooter()
{{/velocity}}

I don't see what would be not ok in the content. The problem is very consistent (it works at all level 1 and no level 2 and further).