On the osmo mobile series there are phones that cannot be detected by the osmo.
For example my iPhone 7 and 7 plus or iphone 6 it can be detected by my osmo mobile units
Tried the iphone 8  and iphone 10 or X

Go to gimbal settings on app
Toggle "Mobile device check" turn it off

Then try restarting everything then use iphone 8 or iphone X it will be detected by the osmo mobile series

PROBLEM SOLVED! iT WORKED FOR ME I hope it will work for you too.

My iPhone 8 refuses to connect with OSMO, I can't even get into Gimbal settings as it asks to connect device?