Marshall headphones Bluetooth connection

Hi,

I’ve recently bought an iPhone 11. I’m trying to pair my marshal headphones to it but for some reason it can’t see it on the Bluetooth. Even though I can pair my Marshall headphones with anything else (Mac book, iPhones). I’ve even uploaded a Marshall Bluetooth app, and it doesn’t see the headphones it’s written “no device found”.

What’s even more strange is that in the Bluetooth of my iPhone 11, there’s all the other device with the Bluetooth on that are seen. All apart from my Marshall headphones .

I don’t know if I’ve been clear I’m what I’ve said but I thank you for the help you’ll give me.

regards,

Eloïse.