Fenix 6 Pro / JBL TUNE110BT headphones issues


I just bought a Garmin 6 Pro and bluetooth a headphones JBL TUNE110BT. I've succeded to pair the two devices via bluetooth but Volme-up doesn't work it always work as Volume-down. Also when I play music, I cannot hear anything with hearphones even if the volume is at its maximum!
Any clue?