I thought that might be the problem, but the hover only works if the submenu is overlapping the parent. Obviously I don’t want the submenu to be on top of the parent, though, so the problem still remains. I’ve been searching around and apparently Opera has some hover issues. Still haven’t found a solution though.
See my answer in your other thread 
Opera has no problems if you make sure everything is exact like I mention in the link above. I never usually have trouble with modern Opera when using dropdowns.