Why no log ?... Do you mean the viewer does not produce any log, or do you refuse to provide the said log ?
Not producing any log would mean the viewer cannot even initialize (which would be extremely surprising, but also a symptom in itself).
I you do not want to provide a log while the viewer produces one, then I'm afraid I cannot diagnose the issue... If you are worried about privacy or something, you may perfectly edit the log before posting it (e.g. replacing your OS login and/or avatar name and/or UUID with "xxx" in an editor), and/or can send me the log in an attachment to a PM.
Also, please, do provide a copy of the About floater system tab info (the one of the last working viewer version if the new version fails to display it), so that I can know what hardware (especially GPU) and drivers you are using...
So, it does seem to start (and thus produce a log) after all ?...
With the little info you provided, I'm left clueless, and cannot diagnose (and even less fix) your issue...