Distortion within a certain frequency range for wireless mics on magic sing 11000

We get this bubbly distorted sound from the speakers on the wireless mics during singing, we have two of these mics and they both do it. It most typically occurs in the higher vocal frequencies, high alto range. It happens more to female singers than male.

I've tried to adjust system volume, music volume and mic volume. Currently we have the mics set at about 4 or 5, and the music volume is higher but balanced, and then the system speaker is higher to compensate for the low mic volume and that seems to reduce the problem, but it still occurs sometimes. It seems as if the mics are extremely sensitive, or that extreme sibilance occurs within a certain vocal frequency range, causing this distortion. Has anyone else reported this, is there anything that can be done?

We had to send both mics back to the manufacturer when we first got them, because they only worked within about 7 feet of the unit. That problem got fixed, but since then we have been having this issue.

Would a simple windscreen fix it? I'm at a loss on how else to fix this, short of sending it back to be checked again and having to pay shipping both ways like we did the first time.