CRM App In Mail Sidebar

CRM App In Mail Sidebar

Hello,
For a long time, we've had the link to Zoho CRM through a button in our Zoho Mail account, on the app sidebar.

But now it doesn't seem to work.  We can still get to the CRM by going outside of Mail, but it was really convenient to access it through the Mail App Sidebar.

Any idea why it's not working anymore?

Thanks!