Layered Nav

Hi,

when using the Layered Nav widget, I stumble upon the following situation.

Products have 2 attributes: vintage and volume and I created variations with these attributes.
For instance
– Chateau Clauzet (product) 2008 (vintage variation) 75cl (volume varaition)

I use vintage attribute for layered nav.
Query Type is set to AND

The widget shows correctly the number (count) of variations for the vintage attribute:

e.g. 2008 shows (2)

But, when selecting the 2008 vintage, I get the message

No products were found matching your selection

Layered nav works with Query Type set to OR.
I did notice that the URL is somewhat different as it adds &query_type_vintage=or
But there’s a bug there too:

If I select 2008 and 2010, then no problem.
However, if I unselect one of both selected variations, the &query_type_vintage=or disappears and I’m given again the message No products were found matching your selection

Tried to use &query_type_vintage=and but that wouldn’t help