There's  a bug in Braintoss for Apple Watch in version 8.0.7.where the AW and your phone can't connect if you have only 1 email address in Braintoss. We are fixing this as we speak but below is a workaround for now:


Add another email (besides the default one) and it should work fine again. 

Make sure to open Braintoss on your iPhone  when the Apple Watch demands information from the phone.