I'm attempting to stretch a piece of audio using time stretch and the end result is really bad. Lots of pops and clicks in the audio.
I thought that this was a feature that has been improved in the last update.
Had to end up rendering the piece of audio in another DAW and then bringing it back in CBB.
Any ideas?

I had a similar issue in the middle of a project.  Try unselecting "fast bounce" and bounce to track the time shifted area.  Ive been meaning to try that, but have not been able to get to it.

There's a few different stretch algorithms and methods on using them. Elastique should sound better during online playback than the Groove stretching that was the previous default. Online and offline rendering are also different. The Radius offline stretching should give you the best results when bouncing the audio, but Elastique Pro works well too. Sometimes stretching can differ depending upon the material as well, but it's likely you needed to tweak something in the project for better results.

When you first do your stretch, it's using the "online" algorithm. This is a quick & dirty render so you get an indication of whether the timing is correct or not, but the quality is not great.
 
This is only temporary however - when you're finished make sure you "Bounce to Clips". This invokes the offline method, and uses the higher quality stretch - but it's not instant, so you'll need to wait a fair few seconds for it to process.
 
The online rendering has been improved with the new algorithms, but will always sound inferior to the offline bounce.
 

msmcleod
When you first do your stretch, it's using the "online" algorithm. This is a quick & dirty render so you get an indication of whether the timing is correct or not, but the quality is not great.
 
This is only temporary however - when you're finished make sure you "Bounce to Clips". This invokes the offline method, and uses the higher quality stretch - but it's not instant, so you'll need to wait a fair few seconds for it to process.
 
The online rendering has been improved with the new algorithms, but will always sound inferior to the offline bounce.
 

The problem is that the audio is worse after bouncing to clips.

Go to Preferences/Playback and Recording. Then select Radius Mix as the offline render. That should give you what you had before the update with the added elastique algorhythm for online rendering.

Sometimes what you're trying to do simply won't yield good results.  Stretching too much will always sound bad.   If your clip just needs tweaking to fit is one thing but to completely put something in that's not even close is another.

I've had nothing but problems with the new stretch stuff. I bounce a clip and it processes the audio data, renders the wave then locks up (or takes so long to finish that I lose patience.) That particular workflow is completely unusable right now. I can only hear the results of the stretch either with the online rendering after rendering the entire project.
 
I had lots of crashes too, which resolved after I uninstalled everything (and I do mean everything, including my MOTU audio drivers) rebooting and reinstalling. Stretch is still pretty foobar though. It may be that the crash issues have messed my project up some, causing the stretch lock ups.
 
Whatever the reason, that's the first time I've had to clean install to fix stability issues since X1. 

stxx
Sometimes what you're trying to do simply won't yield good results.  Stretching too much will always sound bad.   If your clip just needs tweaking to fit is one thing but to completely put something in that's not even close is another.

Yes, I agree but in this instance I can do it perfectly in Samplitude (which is what I eventually did) and then brought the rendered wave back into CbB to finish the project.

could you send us a project that exhibits this problem? We havent encountered this in testing...