I too am having problems with DIVI. I hope there is a solution, the DIVI menu is awful.
Hi, we have checked divi header.php. Here is a small issue which is conflict with others menu. When divi menu is empty or disable then it show all page items in menu list. So, need to customise header.php file. See the screenshot https://www.dropbox.com/s/4tsu2t2p8rkqeeq/divi-issue.png?dl=0. You can try to remove code within red border.
Removing that code from the header file didn’t resolve the issue.
Please post your issue on the support forum- https://www.themeum.com/support
Would be great if it was compatible with Divi, you’d have a huge market if it was.