Kalle Rantaaho
There used to be also "Play FX tails after stop", I don't know if it's there anymore under that title.

I just noticed this reverb tail problem is back now that I am using 2016-12 early release.  I can't find a setting for "Play FX tails after stop".  I have been using Clip Tail Duration = 1.5 sec and I haven't had a problem for a couple of years. 
 
With 2016-12, it makes no difference how long I set that tail duration.  I can set it to 10 seconds and it still chops the clip at the end of the selection, which sounds terrible.
 
It is not an option for me to stretch the clip longer because these are live recordings that typically have applause beginning a second or two after the last note.  It was working perfectly, but now seems to be broken.  I wonder if anybody else has gotten hit with this.  I will try reverting to 2016-11, but the bug might have come in before that.

"I will try reverting to 2016-11, but the bug might have come in before that."
 
I reverted to 2016-11 and the bug is there.  I am not going to keep reverting, but the bug needs to be fixed.  Does anybody know of other configuration settings that might defeat "Clip Tail Duration"?
 
I see that this feature was introduced in 2015 "Ipswitch".  It was brilliant, but it ain't working now, at least not for me.
https://www.cakewalk.com/...wich-Update-Notes#tail

Are you trying to bounce the full song and it just ends at the exact end of the last clip?  
 
What I do is put in another short audio file or midi sometime after and bounce down with that and then edit where the wav ends in Soundforge.

Bloodrocuted666
Are you trying to bounce the full song and it just ends at the exact end of the last clip?  

I am doing a File Export to mix a song to a stereo WAV.  I believe the purpose for "Clip Tail Duration" is to automatically extend my selected region by the adding x seconds of silence to the end of the selection, allowing tile for the reverb tail to finish.  I realize I could hack away at the file and insert the silence myself, but the whole point of that feature was to make it automatic.
 
I should mention I generally work with recorded concerts.  I may have an hour of tracked material.  In the mixing process, I split the program into songs and put fades on each end.  The fade, however is pre-verb, so the verb tail goes beyond the end of the fade-out.  And what follows that point in the source tracks is usually applause.  I'd rather not have to go in and wipe out the applause.  I never had to do that when this feature was working.
 
I noticed the problem because when the export completes, if there was some tail that didn't make it into the file, that "left over tail" is actually audible as the export process ends.  I hadn't heard that little blip for a long time, which got me digging into it.  I think this feature must have broken within the past 2 or 3 releases or else I would have heard it for sure.

cparmerlee
Does anybody know of other configuration settings that might defeat "Clip Tail Duration"?
 

 
I haven't checked it out, but Freeze Tail requires Track FX to be checked. Possibly this is a requirement for Clip Tails as well...?
 
Regarding not being able to extend the clip because of applause, you can Apply Trimming and then when you extend the clip the extension will be silent.
 
And I'm not sure if it's relevant to the issue with Clip Tails, but the rough equivalent of 'Play FX Tails' is now 'Always Stream Audio Through FX'.
 
EDIT: A couple more thoughts...  It's not clear to me that this option applies to playback; the documentation only mentions exporting. Nevertheless, I tried exporting with a tail, and got several seconds of dead air tacked on to the end of the clip with no reverb, so it does seem there's an issue.

brundlefly
I tried exporting with a tail, and got several seconds of dead air tacked on to the end of the clip with no reverb, so it does seem there's an issue.

That's strange.  I get no extra time tacked on the end of my export. 

Source =  Clips?

brundlefly
Source =  Clips?

Yes.  I split a long concert into a bunch of separate clips, and then put fade-in/out on each:

Then I select the clip, which sets the start/end time on the ruler. Finally I Export Audio:

My preferences say 3 second tail, but I get no extra time in the exported WAV file.

FWIW, if I freeze a given track, the freeze operation does perfectly apply the Clip Tail Duration that is specified in the Freeze Options.  But what is broken is the Preferences - Audio Data - Clip Tail Duration, which should do exactly the same thing for exported audio.

I meant Source Category = Clips in the export dialog. In your screenshot, it's 'Entire Mix'