Loosing Collectible Star Errors?

I have been playing the first battlefront game for the ps4 in offline mode and have noticed a strange bug or problem that I can't seem to find an answer for. When I play on survival and collect all the collectibles, I get the star for it after the mission. Then sometimes after I have turned off the system and come back to play when I next have free time, (sometimes a week later) I have lost all of my stars for collecting the collectibles and for completing the missions. Has anyone encountered this problem before and if you do you know how to fix it? Thanks for your time.