Footage being skipped over when trying to watch back

Hi all! My mum has an android, Samsung something or other. When she tries to look back at previous footage, the videos get skipped over, like it just goes mental and skips over like 4/5 and become unviewable! I’ve checked for updates, deleted and reinstalled the app, disconnected and reconnected the app and nothing has worked! Anyone else had this issue and found a solution at all? Thanks!