Some contacts are not added to workflow and we don't know why

Some contacts are not added to workflow and we don't know why

Hi there,

We have a workflow set to trigger when a user is added to a contact list. We recently noticed that not all users were getting the emails.

On investigation we realised that not all contacts are entering the workflow but we cannot see why.

The contact is automatically added to the contact list in Campaigns based on a field update in Zoho CRM. We can see that the contacts are added to the Contact List, sometimes without names. But not all of them are then added to the workflow.

We've also seen the option called 'Missed Out Contacts'. It says there are 21 contacts missed out but doesn't show us who they are or why they were not added.

Any ideas as to why this might be happening and how we can troubleshoot?

Thanks
Craig