Hi Ruta,
I’m sorry you’re running into this issue, but I’ll be happy to help you figure out what’s going on!
Just to clarify, are you referring to recurring events? I’m not exactly sure what you mean by events falling off of the calendar/back end…are you missing past events? If so, I would recommend taking a look at what you have set for your Clean up recurring events after setting under Events > Settings > General. This helps keep your site performance up by automatically deleting instances of recurring events after a certain amount of time.
Please let me know if adjusting that setting fixes the issue for you, and if not, can you please provide some more details on what is going wrong?
Thanks,
Jennifer