Why are my bookmarked videos not saving anymore?

Having issues saving videos to watch later. Booked marked videos not appearing in my book marked video section anymore. Some are disappearing. Tried updating tiktok app. Issue resolved for a day then it's happening again. The videos I'm.saving have not been flagged and if I go back through my watched videos I can see they are still book marked, they just are not appearing in my collections. I also have not filed them into a separate collections folder. I just leave the majority of book.marked videos in the general folder. I have over 5000 book marked videos. Do you think the issue is I've saved too many?