No idea, haven't seen this until now. Hopefully they provide a mechanism for allowing legitimate addins to get around it. Perhaps using a code signing cert (which I do) or an EV certificate would be appropriate. Security has been a bit of nightmare with Excel addins. I've had to deal with false positives on and off again a bunch of times already. First it was windows smart screen, then antivirus vendors every so often. It's a slog...

Typically you can go into the file properties and check the “Unblock” checkbox to remove what Microsoft calls the “Mark of the Web”.

Open us a feedback through the app. We actually read every tiny bit.

Cool. How can I turn off the animated cursor movement in Excel? And Outlook? Drives me crazy. I keep submitting feedback. Even a registry hack is fine.