I have noticed that I can not paint on a plane when a picture is underneath. I have used different filters. For example, the blur. But this does not work. What can I do that this can use?

@michaelstoltz Can you post a link to a full screenshot of your image? This will give a better idea of your situation and image structure.
Even better, you could use a file sharing service to provide a download link for your .kra file so that it can be examined.