I recently got a pair of Bose QuietComfort 35 II and they worked well in A2DP...until I tried to hook the microphone up to my Kubuntu machine for calls. I switched to the HSP/HFP headset profile, but all that I heard was static. Other posts on this site have mentioned lower audio quality, and testing the same headphones on a Windows 10 computer, the audio quality with HSP/HFP is indeed lower than A2DP, but the audio quality that I experience on Kubuntu is even worse. It is literally impossible to comprehend any audio coming through the headphones. In addition, the mic does not work either. The mic only picks up crackly static, not my voice. After about 30 seconds, the profile turns off completely.
Other solutions have mentioned switching between these two profiles with a script or sticking solely to A2DP, but the former doesn't work because the HSP/HFP profile's mic is useless anyway, and the latter fails because I need a mic. I have tested other Bluetooth headphones on my PC, but they couldn't connect to HSP/HFP at all, so the QC35 is the best I've got. This question seems to match my situation somewhat (videos still play for me), but my chip isn't Broadcom. Does anyone have any suggestions or solutions to solve this problem?