Honestly .. .I'm a bit buffaloed about what to put with what due to lack of punctuation and caps. Cute for texting, but not so helpful here since I'm having trouble with sentence breaks.
Let me take a guess at the meaning, and please advise where we may have got it wrong.
You have new Rider 400. BEFORE you updated the unit, it was working correctly with your Sena headset which uses the necessary A2DP bluetooth profile.
After the hands-free update, and with that feature enabled, your phone requires you to keep re-pairing due to lost pairing? Or it stays paired, but keeps connecting/disconnecting by itself? Which connection is acting goofy? A2DP or HFP? Both? A2DP audio works fine if hands-free is disabled?
What phone is involved here? By rights, it should manage two concurrent BT connections of different profiles, but I'm wondering if it's not capable of this. It sounds like your phone may be bouncing back and forth between the two connections.