You should have either received an array w/4 values or false. You received a '1'...
Ok, I assumed as much but began doubting my (limited) understanding of PHP/SMF sources. I'll add more monkeypatched debug output.
Whatever is causing this, it behaves differently when directly
print_r'ing to the page, I'm seeing array data there (but having other problems, like I can't pre- or append context messages before the printed variables, for whatever reason).
Interestingly, once I added (file writing) debug code to the previously working BoardNotify function to look for any differences,
that function exhibited the bug, too.
Got other things to do, this is leading me nowhere.