When I flex a part that has many small feaatures on it the part rebuilds.  I then check the part and it always shows face errors.  When used later on to create tooling parts I cannot perform a split.  I have tried all the options in the flex command and can move the failed faces around the part but they are always there.  I can suppress the flex feature and rebuild the part with no errors.  Any ideas on what may cause this issue?