I ran some tests with a project upgraded from 4.5.1 to 4.6.0 built in DebugGame configuration, and even though I was able to trigger a breakpoint, it looks like it is something different from what you were seeing (mine is failing in some Internationalization code that I believe I have seen before, just need to remember how to resolve it).
How have you set up your reference to the Blueprint Struct that you are using?