Your feed rate may be too fast. Take the (radius of the corner + the radius of the tool) x .31 x RPM and that should be the MAX feed. If your feed rate is already below that, try just the corner radius x .31 x RPM.
Typically radius corners can be ran faster, but if the corner radius is too small, it needs to be slowed down.
If your are using a HAAS control check your G187 E value. Typically it is set to .050, you may want to make it smaller OR, change the G64 milling mode to G61 in position, and see if that works for the corner problem.
Those are my best guesses, not having more information.