Approval of this iphone/mac goes back and forth

I sign into the Mac to approve the iphone, it asks whether I trust the phone,I say trust,the Phone simultaneously asks whether I trust the Mac, I trust. However, no matter which I trust first, and it happens every time I sign into iCloud to approve my iPhone..the phone is left without its code/given the code to authenticate it as a device. and the whirling dervish of annoyance states that it is waiting for approval. It is in my settings as an approved device however, it is just that the phone itself cannot work that out.

I have signed in and out, updated etc to no avail.