OS 10.10.3 and DesktopVideo 10.4 mono audio problem

Hello,
I've searched in the Blackmagic forum and it appear i'm not alone to have this issue. So be careful.

I've a problem in a new configuration with FCPX 10.2 on a MacPro (Late 2013) with an Ultrastudio 4K and Desktop Video10.4.

I Can't hear media with a Mono Audio. If it's a stereo I've no problem, sound is alright .
If I put the clip in a project I can listen the clip (Project in FCPX is only Stereo or 5.1). As Soon as i play the mono audio clip in the browser, i don't hear it thru Ultrastudio, but if i choose internal audio output of the mac, i can hear it.
If I go in the audio tab in the inspector and choose left or right instead of mono, I can listen the audio of the clip.
What happened ?
forum.blackmagicdesign.com/viewtopic.php...653&p=205438#p205438

I'm waiting for their responses

See if this does anything

www.fcp.co/forum/4-final-cut-pro-x-fcpx/...g-bug?start=20#62908

It works !!!
Thank you Tom and everybody of this powerful forum !