Hello guys, as suggested by Moss, i’m opening a new question to put it cleaner.
It turns out that in TUnion is declared a log category (Union.h):
DECLARE_LOG_CATEGORY_EXTERN(LogUnion, Log, All);
that is misssing the relative implementation (Union.cpp is actually commented out).
To actually use a TUnion in most of the cases you need to add
DEFINE_LOG_CATEGORY(LogUnion);
in your custom .cpp class’s file.
For a complete case explanation, you can look here:
I hope you’ll open a ticket about it.
Sincerely, zamy