Synchronize with Google calendar

Hi Zoho Recruit Support team, I got an issue here and I need your support. Recently, I cannot synchronize the Zoho calendar with Google Calendar. I mean, when I set up an interview, I can only view it in the Zoho calendar but it does not automatically synchronize with our Google based Calendar. We could do it before. Please check it out and let us know what is wrong with that function? Thanks and best regards, Khiem