Graphics do not export correctly from Pages to PDF
I am creating a cover for my book to upload to KDP publishing. I am using Pages to do it because that's the best software I have right now. Anyhow, when I export, some of the images I created by combining shapes are not showing up as well. In the first example image below you can see that dark vertical line appear in what should look like a more natural 3D shape. Also, the corners at the top are off. I created this using a diamond on top that covers two rectangles. If you look at the second image, you will see how it looks in Pages. I know I'm not using the most professional software, but does anyone have any suggestions as to how I can eliminate this issue?