Hello,
1) What compatibility issues of the 5.0 version of Royal theme and WP 5.1.1 did you find? Could you explain in more details?
2) I don’t see this problem on the updated site https://gyazo.com/8a96979aea6d5e1d8074e02fb94fc36b
3) Notices that you have caused by third-party plugins http://prntscr.com/ng4ycw Disable them one by one to find out which one causes the issue.
Regards