Sharing slides as virtual background

[DDownes]

I have been using the feature "PowerPoint as background" for a few years and I have never had a problem in sharing my slides that way, and stopping and restarting the share with the same slide deck. Over the last month, if I stop the share and try to restart using the same slide deck, I get a message that says, "This file is in use. Enter a new name or close the file that's open in another program." 

The PowerPoint file is not open on my laptop or in any other programs, but I can't reopen it in Zoom. I would appreciate guidance in solving this issue as I love this feature and use it frequently. 

@zoom