Tracks not saving for more than a day

I have a 2013 Terrova 55 with Link. It was working great a few years ago and would hold 6 tracks forever... then two years ago i added a Humminbird FF and linked with an ethernet cable... I got rid of the Humminbird because the Canadian fishing maps sucked and put in a new Garmin.. I should still be able to save 6 tracks and it will , but not for longer than 1 day.. on day two all tracks are gone. I have two new 12V Gel Marine batteries in parallel that stay charged each day with a dual bank charger. I hope I didnt fry something by not unplugging it when I charge it. I just have been turning it off.... I checked all connections. Spot lock and everything works great... ???? Please help