The ICS file was created by saving/exporting my calendar from Outlook. When I select the file in the zoho web interface in outlook nothing happens. Not even a error message.

I have to be honest I have almost had enough of zoho and on the verge of going back to office365. The reason I'm trying to import this ICS file is because zoho active-sync is too unreliable. Ideally I wanted to simple drag the appointments and contacts between my Exchange account and Zoho account within outlook. But the results are too hit and miss.