This is related to [Link Removed], and possibly the same issue. It is still not possible to open a generated.h file from within a project solution. I was able to reproduce this in both a binary Engine installation, as well as in an Engine built from source code. Two co-workers were only able to reproduce this in an Engine built from source code. Binary Engine installations worked correctly for them.
An error is displayed stating that the file cannot be found in the current directory or build system paths.
Visual Studio opens the generated.h file.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-67548 in the post.