We've created this Forum Thread with some workarounds and advice to assist you in publishing you ebook.
Need help with creating print book cover
I am unable to add my cover photo. I have adjusted the picture size, I think, and it still will not add the image. I need HELP to complete this book.
This is the message I get after uploading a picture for the cover page.
Your cover file is 246 points wide by 164 points high, but these are not the right dimensions. Your cover should be uploaded at 1242 x 810 points.
Please tell me in lay terms how I resize my image using Microsoft picture editor so it will work! I need to know the size in pixels.
Also, each time I go back into My Projects, I have to resave the book file to get to the cover page.
I look forward to your response.