Bluetooth: intermittent mSBC playback

USB dongle (rtl8761bu chipset, I believe):

Bus 005 Device 003: ID 7392:c611 Edimax Technology Co., Ltd Edimax Bluetooth Adapter

Headset: Audio-Technica ATH-ANC500BT.

Fedora 35 packages: pipewire-0.3.40, wireplumber-0.4.5.

$ uname -r
5.15.8-200.fc35.x86_64

AD2P sink & CVSD work fine, but mSBC playback works only sporadically: sometimes there's clear sound for a few seconds, then silence--if I switch audio profiles (mSBC -> AD2P -> mSBC) in blueman--then it starts working again; sometimes there are no problems for 1-2 minutes & then suddenly there's no sound.

Tried to use rtk_btusb driver (from edimax website), while blacklisting btusb, but the results were the same.