audition a region?

Hi ardour users and developers!
I’m running ardour 2.5. When I try to audition a region via button-3 pop-up menu (1) the playhead moves straigth to the beginning of the selected region, (2) all the mix is played, until the end of the region (3) the audition red indicator doesn’t light.
I could audition a single region in previous releases with no (1), (2) nor (3) behaviour.
I have the audition ports connected to playback but even if I disconnect them it’s the same, as if “audition” meant “master playback in the selected region interval”.
I’ve checked the preferences window but I can’t see an “audition with mix” or similar option which I should have deselected.
Any ideas?