No audio feedback?

But if you have the music version of the watch, why do you stream audio from the phone? Maybe it would work if you had your audio connected to the watch.

Maybe it would but the music version whilst useful for offline music cant do live radio or that sort of thing i use on long runs.

RDW said:

Any idea what im doing wrong here ?

Are you forget to pair your BT headphones to fr255m? The watch has no speaker itself. All works flawless and without phone on my fr255m. 

Its connected to the phone at the time and the manual and Garmin web FAQ state it should play through Garmin Connect via the phone speaker or paired BT.

From the manual page 71:

"You can enable your Forerunner music watch to play motivational status announcements during a run or other activity. Audio prompts play on your connected Bluetooth headphones, if available. Otherwise, audio prompts play on your phone paired through the Garmin Connect app. During an audio prompt, the watch or phone mutes the primary audio to play the announcement."

https://support.garmin.com/en-US/?faq=7GKQD46gnB6OqTv10LutJ9 also confirms it

For the models listed below, it is confirmed that the audio prompts that will work with the Garmin Connect app to your Paired Smartphone speaker is: Lap, Time, & Heart rate

• I have the same problem. Sometimes the audio alert is working, but sometines not, and I don't change anything

Same thing for me, sometimes it often works not.