Two glinting objects on a cloudless CA sunny day - one disappeared, the other stayed visible for approximately 30 minutes

I was out in the backyard watching a pair of eagles when I noticed a pair of shiny, glinting objects behind the birds. The objects appeared in a vertically offset formation traveling south to north - the lower object flashed and then disappeared and the higher object continued to move very slowly to the north. The fact that it was holding very slow and steady flight path, and glinting in the sunshine, was unlike our typical air traffic and wasn't showing up on our FlightRadar24 app. We ended up taking video with two separate cell phones, re-watched the videos several time and have no idea what we captured.