Hi Ken,
An update on the following issue that may be related to the WDA ,
Specific Error message logged in Appium console:
Enqueue Failure: UI Testing Failure - Failure fetching attributes for element Device element: Error Domain=XCTestManagerErrorDomain Code=13 "Error copying attributes -25202"
There are also a few bug reports logged to Apple, that state there are multiple causes to this and that anyone receiving this should also log a bug report.
I have found that in some cases the device is returning the element but the specific element is not yet visible on screen, this could be caused by animations during transition. In my particular case a row is returned and the test click's on the row but instead of the expected behaviour the 'Enqueue Failure' error is returned causing any further test's to fail.
I have decided to put a dirty hack in and wait for 2 seconds before clicking an element just so I can run all the test's over night.
This is not a fix, and I will certainly be looking at alternatives, but at least I'm getting closer to the root cause.