It is no longer possible to first right-clikc to look thru your sights and then hold the right mouse button down to hold your breath, the guns just lowers itself like you were clicking out of sighted mode.
if you are not looking thru the sights then you can hold right mousebutton down and go directly to "zoomed-in"/holding your breath.
This has been the case for a few dev.builds now.
Get in game, right click to get sights up then hold right mousebutton down to try to hold you breath.... gun goes down instead of holding your breath.
Get in game, hold right mousebutton down when you are not looking thru the sights ... gun is now raised and in hold-your-breath-mode.
Bind "hold breath" to something else, like the button right of Lshift. Now you can zoom and hold your breath independently.
I tried binding another key, it didnt work at all for some reason.
Then i messed around with the presets and finally set it to ArmA3(which it has been all along), and now it suddenly works like it should.
Talk about weird.