Thanks for checking! The flare+ has an audio confirmation of connection feature. It does not sound for pairing. So I can confirm that after turning bluetooth off then on on the U1 it is pairing with the flare+ with no audio feedback. It is the same even after forgetting the flare+. So that is a bluetooth connection problem.
Now, maybe I should open a new thread for this, but with my other speaker (SL1000S) there is no issue with bluetooth pair/connection. I have audio confirmation of connection from the speaker. Here, the speaker is listed in the U1 bluetooth devices as paired and connected as a media device (headphone icon shows in the U1 Advanced Settings Bluetooth config). However the audio does not switch to bluetooth. So there is an issue here where the recognized and connected bluetooth speaker doesn't become active and is not in the U1 Settings (not Advanced) Audio Devices Manager -> Output devices - I only see "Auto" and "hdmi". In the Advanced Settings, there is no mention of Audio Output devices.
So again, thanks for your help, but I see no other options given the limitations of having a non-rooted device - can only see as far as the limited utilities allow.