CM11, prob. with 2 paralel audio sources in earphones / speaker

Hallo,

i've updated my I9000 to CM 11. Everything works really fine, from the first day.

I have just one problem (may be), and i dont know how to solve it. I use the App Mapmyrun and runtastic for jogging. While i am jogging i listen to fm-radio with my earphones. Previous i listend to radio and when runtastic have to tell me sth the radio was muted and i could here ust the app runtastic in my earphones, when runtastic was ready with talking, i could listen to radio again.

Now:
Same procedure, fm-radio and runtastic are on air. When runtastic have to tell me sth, radio is going muted - but runtastic sound comes out of speaker and not from the earphones!? As soon as runtastic finish talking over the speaker, i can hear radio in my earphones again.

I tried other radio player and combined it with other jogging apps.
I tried out to change settings, in apps and on my device - betterment.

Does stb know this problem / bug and can tell me ow to solve this? Maybe there is a bug in CM 11 with 2 parallel audio sources?

Thanks in advance