GMcT
Why don't the developers just add an End of File/Project feature?
The documented workaround of placing Now Time at the end and selecting what you want rendered is laughable considering this touted as a "full-featured professional DAW".
 
Oh dear, no doubt all the Sonar zealots, including people marked as new users (like me) who seem to know everything about everything, will castigate me for that comment.
They usually tell you that either your computer is a piece of junk or else they imply that you are an idiot for criticising their beloved DAW.
That's why I've given up on the forums: too much vitriol.
Apologies to the decent people who are constructive and genuinely try to help people. You are in the minority, but are very much appreciated I assure you.

I had some frustration with this issue as well, but finally figured out that, as Craig has pointed out, Sonar will render up to the last event in the song. It took me a while to understand that automation events count as well. I have experienced spurious placement of automation events as well, so I'm glad that Craig has found a way to repro the issue and get it looked at, thanks for that Craig!
 
By the way, yours is the only vitriol I see in this thread. 

Yup it stops at the last event in the song.

But often when you are working you may end up inserting an event by accident somewhere, then you have to hunt around play detective.

Being able to set the end of the project would just mean you can forget worrying about this sort of thing and just make music. Set and forget has an obvious advantage here. It would make a fine enhancement.

While this is all an entertaining thread in a pointless sort of way, I started this thread with a request for someone to confirm whether the double/stacked automation event is what prevents "cut automation" from sometimes deleting spurious data. Fixing this would eliminate needing to "play detective" while you're waiting for feature request 45,391  to be implemented. 
 
I'm still waiting...to quote myself:
 

anderton
Can anyone confirm?

Yes I can confirm this. It behaved exactly as you described for me.
 

Thank you! I always appreciate solution-oriented people. 

I don't think so. I think Sonar is just broken. I've had projects with no automation and still have the problem. Although, your node theory could be what breaks Sonar???

Guitarpima
I don't think so. I think Sonar is just broken. I've had projects with no automation and still have the problem. 

See post #3. I already addressed this, but I can understand how signal sometimes get buried by noise.

Hey Craig, just to be clear I am confirming that you can't delete the automation out there past the end when it is on the same time and curve without moving one of the nodes. I can't really confirm that you have solved the mystery yet, although I think you may be on to something

teego
Hey Craig, just to be clear I am confirming that you can't delete the automation out there past the end when it is on the same time and curve without moving one of the nodes. I can't really confirm that you have solved the mystery yet, although I think you may be on to something

Well, thanks to your help, I consider it progress to have a confirmation on one reason why you can't delete the "end of song" automation. Doesn't mean there aren't more, but I haven't found any yet. It would certainly be helpful if there was just this one reproducible issue. That can often lead to a fix.
 
Again, props for assisting instead of complaining.

A script or command to remove all events on all tracks past a certain point on the timeline would certainly be useful to me. Sorry that I can't confirm the behavior you describe, Craig, I'm out of town till next week.