The PNG file asset shown in the dialog box below is already gone:
I cannot find it within the Asset Manager at all! That’s the entire problem. And every single time I close and then reopen my Blocs document, it gives me that dialog again!
So if you know of another way of finding it outside the Asset Manager (and no, I don’t see it on the page either), then please let me know. I’m going crazy with this dialog.
UPDATE: I just sent you a copy of my document (new bug report ticket) so you can investigate further.