Jfreeman;
I had that countless times with softer tips. Especially zebrano overlays had troubles with ff. But I even had padouk splitting on me, but only on narrow nocks without sidegrooves (yet).
I suggest you sand your overlays off with the beltsander, glue on new overlays, made from harder materials. I've had great results with wengé, ipé, purpleheart, but also with horn. Bone, antler and other rock-hard woods will do the job aswell.
many glass 'ff-proof' bows have phenolic overlays. I haven't tried them, but you can't go wrong with phenolic.
Nick