VoiceThread is a third-party integrated interactive collaboration and sharing tool.  Blackboard VoiceThread links to not import correctly into Canvas and will need to be recreated.  Whenever you get a new Canvas course site you will always need to recreate your VoiceThread links.

Tip Your VoiceThreads exist independently from Blackboard/Canvas.  You do not need to recreate the VoiceThreads, just recreate the link.

For more info