EAAccessory - bluetooth connectivity issue in specific region

One of our customers in US unable to connect to our device.

current status: able to discover device, when trying to connect it throws an error " (error :Error Domain=EABluetoothAccessoryPickerErrorDomain Code=1 "(null)") " tried with different models, iPhone 11, iPhone XR, iPhone 15.. result is same.

But It is working fine in Asia regions.

Note: External accessory framework protocols has been added already in Info.plist. ( which has been registered in the MFi Program)

Any help greatly appreciated. Thank you!