The 20S Audio Multitasking feature would perform incredbly better if the dual BT modules used a complementary frequency-hopping plan, thereby preventing them from hopping on to the same frequency at the same time. Presently, the dual BT modules do this so often that it renders the feature unusable. Simultaneous intercom and A2DP sessions cause the intercom session to be unstable, often causing it to terminate. The frequency hopping can be heard over the speakers, and perhaps that's a symptom of another related issue, such as insufficient selectivity and sensitivity due to sharing the same antenna.
Like others on this forum have discovered, the Audio Multitasking, in its present form, is not usable.