I have a flow that sends an adaptive card with an image that is a thumbnail from a SharePoint file. When I first send the cards the image and the on Click actions work, but after the weekend or a few days the images can't be seen or clicked on. I have previous tests with image URLs with just the Microsoft logo (not from SharePoint) that are still showing in teams. I have tested all three thumbnail sizes as well and the issue is consistent across all of them. The files in SharePoint haven't been moved or edited or opened even since the cards were sent. Any idea why this may be happening?
