Unable downloading content session and summary log on kolibri version 0.12.2

After installing kolibri version 0.12.2 in May 2019, users have been logging in since May, and now in July when I went to a school to download content summary log this is what I get as shown in the attached picture. It only shows that two users logged in, but leaners have been logging all this time. What might be the problem?