Series does not work well

For some months now, the "Repeat" option for events has not been working properly. It lets me create events that repeat in the time that I select but the problem comes when I want to edit them, if I want to delete an event of the series, it lets me delete one but when I delete another one the first one reappears. It does not work well, the same happens if I edit them, if I change the description of an event included in a series when I save it, it returns to the way it was initially. HELP