1 Tradfri Bulb out of 10 won’t connect

I’ve just purchased the premium App as I wanted to support the developers, this a great app!

I’ve managed to pair 9 Tradfri bulbs but one is refusing to pair.
Initialising the touch link the bulb starts to pulse, and after running a search nothing shows up.
I’ve got the Hue hub right next to the bulb and I’m not doing anything different to what I did with the other bulbs.

Would anyone have any suggestions?