I am getting a different behaviour here. I have even created a new, default C++ MFC app in VS2010 with VA 2023 to make sure that my test project settings were not a factor here.
With the line of code:
_tcsclen(STRING_SEPARATOR);
when I place the caret into the macro "STRING_SEPARATOR" the VA definition field shows:
That makes sense, I can see how this would be connected, but so far I cannot reproduce the problem with deep macro parsing turned on, and I am not sure why. Are you seeing this in all places where you use the macro "STRING_SEPARATOR" or only some times?
Can you please export your VA and IDE settings and send them to me:
VA Options -> Performance -> Export Settings IDE tools menu -> Import and Export Settings -> Export selected environment settings
I can then import them here and see if I can reproduce the problem.