I'm not sure why this is happening to you, it could be many things, but I could suggest different approach. Your part appears to be symmetrical, cut it in half or even quarter and mirror the entire finished body.
I did mirror a simple flange across the plane as you have done with out issue, can you upload your model?
I'm not sure why this is happening to you, it could be many things, but I could suggest different approach. Your part appears to be symmetrical, cut it in half or even quarter and mirror the entire finished body.
I did mirror a simple flange across the plane as you have done with out issue, can you upload your model?