Connect + no longer opening since iOS update

For some reason ever since the update to iOS 11.2.5, my JBL Connect + app (that previously worked fine) no longer works. It now starts on a screen that directs me to turn on the Bluetooth on my iPhone X, despite it already being turned on and paired with the speaker.

No matter which order I do things in (I’ve tried turning off Bluetooth and then starting it when the Connect + app asks for it, but it still doesn’t think I have Bluetooth turned on).

I’ve tried restarting my phone, telling it to forget the speaker(s), resetting the speakers to their factory settings etc. No dice.

The main issue I have is that I use two Flip 4’s for the stereo feature but I can’t turn that on unless I can access the app.

Can anyone help or has anyone else had problems since the iOS update??