Cannot view Zoho Calender Events for all owners

Cannot view Zoho Calender Events for all owners

We use the calender to assign events to each other within the company relating to cases.
I have just tried to create an event and assign and the system seems to have changed. The calender no longer lets me view my colleagues calenders so i cannot see their schedule. Creating the event is also different and although it will allow me to change the owner to my colleague, it means i can no longer see the event to edit etc.

Can someone please advise on how we can all view each others schedule of events and calenders as this is an important part of our process.