I am getting this error when trying to download the flyer in PDF format: 1 asset failed to upload. Please delete the asset marked with the failed icon and re-upload it or try a different asset. (Failed audio asset will have a gray bar.)
The "failed icon" can sometimes fail to show if the image is cropped (or beyond the page bounds). Here's an example:
You might want to double-click cropped images to check for that.
But if you still can't figure out which asset the message is complaing about, please send me a direct message and we can set up file-sharing for further investigation.