considering freeriders land from stupid heights on standard 3X 32 spoke wheels and they survive lots of this abuse if correctly built I would guess the problem lies with the way the elbows are leaving the hub flange.
is large flange diameter why rohloff spec 2X lacing? to avoid a sharp bend ath the j or have the nipples at an acute angle in the rim?
I think you can also use washers on the spoke/flange area, no idea if that will help or make things worse..
I’d check for any sharp edges in that area as well that could cause a stress riser to form, and gently round off any sharp contact points.