Always something new with Inventor! Above is a multi-body solid .ipt (proprietary, sorry) I originally created a series of work planes through the original solid and did a series of sketches on them using project cut edges. Extruded each sketch as a new solid, no problems. I have now offset as a surface the original solid (to allow for manufacturing shell to build up to original surface) I am now doing a second set of sketches on the part faces to project my offset surface, most are fine, then occasionally I get this.
I am clueless here, has anybody else experienced this one?