This is the nine year-old link I've saved for this - Solved: Re: New VI - default window size - NI Community
It behaves oddly in that if you change it and close it before saving, it won't prompt you to save. Anyone understand this?
Update: I compiled an executable with ShaunR's help. My LabVIEW VI (LV 2017) communicates fine with a simple C++ program, but my executable doesn't. I found a workaround (turn the "keep it simple" boolean off, to use the workaround). Still, I'd like to understand.
The C++ sharmemtest.zip uses Microsoft Visual Studio 2015 and boost (version 1.76.0, if it matters).
sharmemtest.zip shmem_testr.vi
Just slap an 'Always Copy' node after the constant in the second case and it is all good (LV10). They should probably change the icon of that function to a band-aid. (Of course the number of places you need this is supposedly declining, but it is still good to know for those of us stuck with old versions).