Problem with calendar in block view

Hi

I have been having a problem with the calendar in block view, I posted 2 months ago in the calendar module forum (https://www.drupal.org/node/2866296) and after getting no response, also requested for help in the general forum, but with no response up to now.

The client noted that in block view, as shown in screenshot (details in above post), if you have more than one event in a month and clicked one of its links, it shows on the respective page IN SOME CASES other events in that month squeezed into the same box with the event for that date.

I have another site I made and created the event content type manually, unlike in OO-based sites where this comes already created as part of the package & there, everything is OK.

I have no explanation what triggered this or when it came up. The block view has been deactivated until further notice.
The full page view of the calendar on the other side is OK.

If I had created this manually, I would have dared to delete & re-create the content type & related calendar, but I have no idea what that would mean to the other related Openoutreach functions.

How can this be solved? Could it be related to OO?

Thank you in advance