This is most likely a magnetic calibration issue. Here are some steps you can try:
1.Perform the magnetic calibration using the CHR Serial Interface tool
2.Zero the gyros (CHR Serial Tool command)
3.Set the magnetic reference (command)
4.Relocate the UM7 to an area at least several feet away from anything steel or electronic. Sometimes even small stainless steel parts and screws can be magnetic enough to have an effect.
5.Reset the EKF (command). The EKF usually needs to be reset if any configuration settings is changed.
6.Check the output of the health data registers (you can graph these). The Accelerometer and Magnetometer will report if they are out of range which tells you something is up.