Remember this is a filter in Beta so these issues will most likely be resolved soon.
The selection window can be confusing and currently has issues so let’s dive in to fixing said issues.
Currently if you click to select an image it sometimes posts an error saying that this image cannot be used. I’ve found that clicking out/canceling the window and then reopening the window can sometimes solve the problem but I put that as working about 50% of the time. If this method doesn’t work open the source image in photoshop.