[Alfred]

Loraine is right, practice and watch the arch of your fingers. Also look at the angle of your wrist. If your wrist is bent too far your palm will drop, and your fingers will sort of straighten out to make the reach, and this can cause issues with muting as well.
Lots of times these issues can come down to posture… back effects shoulder angle, effects elbow angle effects wrist angle effects finger arch and boom string muting.