3NT has some serious trouble when the defence cash the first five hearts.
I guess after (2H)-3H, South should not be showing a stopper having already bid 1NT on Qxx, so bids 4C, and North bids 4D or 5D depending on how keen he's feeling. Over 3H you take the punt or you don't.
Admittedly the odds on 5D are pretty poor, needing diamonds to come in plus the spade guess.
At the table it was wimp city. West picked 2H, North picked 3D, South passed. No issues making that
ahydra