Sequoia and iPhone mirroring problems.

My Iphone mirroring quit working today. When I launch it on my MacBook Pro, it tells me to lock my phone before I can connect. So I lock my phone, then the pop-up tells me to unlock my phone and follow the instructions on my phone...then the Mac screen pops back to the screen that says I need to lock my phone before I can proceed. And..oh by the way, there was nothing on my iPhone screen "to follow" as prescribed. I'm really confused. It was working great the last time I used it.