Thanks to all who posted! I called Jack at ERA on Friday and yes, there is a "trick"
Shimming is required under the striker plate (the black metal base plate that holds the striker post). But the trick is, you shim only the back two holes. this tilts the striker wedge in a way that causes more positive engagement with the latch. Use shims or washers to shim it 1/8" for the correct tilt.
Beautiful day, sunny and temps in the 60's later. Going for a short ride
Sam