Append Tool - 000117 : Warning empty output generated

I recently had to reinstall ArcGIS (10.2.2) and I am now having trouble running the Append Tool. I am trying to append a point Shapefile into a point Feature Class. I have completed this process hundreds of times, but for some reason after the reinstall I am getting the error message "000117 : Warning empty output generated." I have tried it multiple times with 'No Test' Field Map options on and off and get the same result each time. Both data sets have the same projected coordinate systems and I have also tried selecting only a few samples and still getting the same result. Any thoughts?