After deploying Maps+, I'm able to do a lot of things, with the exception of drilldown.
I have enabled it in the Format Visualization settings, as per documentation, and I've filled the Edit drilldown form, but when I double click on a marker, all I get is a zoom in (or, sometimes, nothing at all). I've also tried to convert the panel to HTML, and tweaked around it, but the drilldown does not trigger.
One strange thing is that, in the Edit drilldown form, I get this warning:
This custom visualization might not support drilldown behavior.
Then I save the panel, and nothing happens on the double click.