It opens briefly and then disappears. It worked up until yesterday. MacBook Air 2014, running El Capitan.
I’ll send you logs or whatever if you can tell me where to find them.
Can you try deleting app and reinstall from the Mac App Store?
Same here. Uninstall and reinstall from website works.
Alex
I think this must be due to:
http://mjtsai.com/blog/2016/02/16/more-mac-app-store-certificate-problems/
I also did battle with App signing yesterday and thought that maybe I broke things. But I guess its happening to other apps and is relate to the expiration of some intermediate certificate… no I have no idea what that really means! 
But from what I can tell … NOT MY FAULT. Yeah!
Seems the easiest fix is to just reinstall from app store.