delete the problematic eyebrow and duplicate the good one, put a -1 in the scale (normally -X) and regroup the lot, also check the outliner making sure there is no history lingering about as sometimes it does.
Cheers Myth
Custom built W10 Pro 64 bit, Hazwell Intel 5820, Asus X99 MOBO, 32 GB DDR4 Ram, EVGA nVidia GTX1080 Founders Edition, 512GB SSD Primary HDD, 16TB Storage, 27" Samsung 4k Display. Wacom 27QHD, Oculus Rift CV1