I had the same issue, then I found this thread: https://www.reddit.com/r/canva/comments/1bvjwst/exported_canva_images_add_xrd_information_in/
It happens only with JPG images from Canva. Annoying, yes. But the fix in this thread worked! Hopefully, Canva resolves it soon
I followed exactly the instructions in the link you sent me.
In fact, following the instructions of this page, all I did was choose the Display Conditions as Post Type is Posts. And chose the placement as header, as instructed.
I have also removed the placement in the middle of the content now, but the ads still don’t show.
Please note that all I want to do is display Auto Ads only in my posts. Could you please tell me what I am doing wrong?
