hi mariuss.

There are many reasons why events didnot displays for guests.
Guests can see the title of coming events?
If not, check "Blocks&Groups Admin".

If the body is only invisible, check the status of the events.
Guest can't see any private events.

You'd better check the "Category's permission".
Events which has categories is not displayed against the members of groups which didnot have permission to access the category.