Hi,
Even after adding the correct includes, I could successfully build, but I kept seeing a lot of red underlined text caused by the intellisense. For those that have the same issue: I just found a solution that worked for me here.
So if you have all the necessary includes and still see (false positive) errors from intellisense: try changing between Development Editor and Development in the dropdown on top of visual studio. Building the project after changing between those values solved it for me. By this I got rid of all my red error underlines! Apparently those red lines are also called “squiggles”.
Apparently (from what I read) this behavior could be sometimes caused after updating a .h file above the UCLASS declaration.