A recent update to the linux kernel introduced a regression that causes an erroneous mtu handshake between some bluetooth audio devices and the system. Even though the audio seems like it is playing, the bluetooth device can’t play anything because of that. If you revert your linux kernel to a version that is before 12th of June, you can resolve the issue for now, until an official kernel update fixes that (i dont know when).
Or if you can use AAC as BL codec, use that. I think it is not affected. Only SBC.