Hi worg3 - I gave it a try and it seems to be working fine for me with the Aug-8 beta. 
 
You probably don't have the plug-in files for that custom command copied over into the new beta release's folder. 
 
When you install a new beta release, it goes into its own folder, and you need to copy over or re-install any custom plugins that you want to use such as CloseCurve. 
 
There will be 2 files for the CloseCurve plugin:  CloseCurve.htm and CloseCurve.js, copy those over to the new beta's installation for it to work, they go into the \commands subfolder. 
 
In the future I want to improve the way plug-ins work so that you would not need to copy files over into new installations, but currently you need to do that. 
 
   - Michael 
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