User HInts (mouseover hints) work in Windows 32-bit, but not 64-bit

I have been fighting this for a while now. When I compile my 32-bit app, since the main form has ShowHints checked and all their children have ParentHint checked, they display fine. But when I recompile for Windows 64-bit, they don't display, even though using the same source. Is there something special I need to do for the 64-bit compiler to show hints?