Filtering show for certain value page with empty values sometimes not

In domotiki I would to use the filtered format for filtering enterprises by protocol. When I select one value (a protocol) like 1-wire results shows only enterprise which propose this protocol and that's the good behaviour

But unfortunately when I select the protocol Rts, the result shows enterprise that don't propose anything(for which the properties "Protocol is empty) and of course entreprises that propose Rts.

You can see here what I mean.

Any Ideas ?

Thanks in advance

Nicolas NALLET (Sémantiki)