Agree that the logs will provide a clearer path for help. There are quite a few extra moving pieces to worry about once you get into running against a physical iOS device and, in my experience, its not a super stable arrangement even when it does work. It gets easier with a little experience but, things will get stuck or end up on the wrong version and suddenly automating iOS feels more like trying to get the chevrons to lock on a StarGate.
Without the logs to identify your unique situation, I can make a couple of stabs in the dark:
Uninstalling WDA from the device, rebooting, and reinstalling WDA from XCode has cleared up some unexplained issues for me in the past.
I was having what looked like WDA issues after a certain Appium version upgrade. It turned out to be a problem with auto-launching ios-web-debugging-proxy (IWDP) on startup. Manually launching IWDP with a specified port and feeding that port to Appium cleared it up for me.
Good luck!