I have CBT enabled on a VM (both in VMware and in vmPRO) and can see the pancbt files in the export folder - but each time a backup runs it completes a full backup.
After completion the flat.vmdk file has a recent timestamp but the pancbt.vmdk file doesn't update.
Is the SmartMotion backup policy 'copy mode' set to 'one copy' or 'multiple copies'? If you want to use CBT try changing the 'copy mode' to 'multiple copies'
Also, you won't see the timestamp on the -pancbt.vmdk files change on in the \\vmPRO\export folder until the file is opened/copied. Try copying the -pancbt.vmdk file to your desktop or another folder and you should see the timestamp update.