Starting elevation is +/- almost 200 feet

(there was a thread on this, but it was locked)

I recently purchased an Edge 130 to pair with my Varia radar - it's awesome. However, the starting elevation for my rides varies every day. The ground level at my home is at 853 ft - so, about 860 ft when checking on the railing of my deck.

When I start a ride, the starting elevation can be right at 855 (or so) or as high as 1060 ft. A few days ago, I manually entered 860 ft while on the desk. I went for a ride later that day and it ended back at my home at 903 ft (so, not a huge issue). The next day, I didn't check before starting but it started and ended my ride at 1067 ft. The next day, it started my ride at 850 ft and ended at 960 ft.

The second ride (that started and ended with 1067 ft) was following a course I created from a ride a few weeks earlier. During that earlier ride, my started was about 850 ft and end was 915 ft. So, that is not the reason the second time through that course was so far off.

Does anyone have any suggestions? Should I just exchange through Amazon? Open a ticket with Garmin?