Please see attached sequence of images (in chronological order) showing that with an existing contact already in Books, there is a failure to update that contact.
The workflow uses a router. Where the Contact ID does not already exist, the router employs 'Create a New Contact in Books', and this part of the router works (with a few anomalies - see below)
The main problem is with the other part of the router - where the Contact ID already exists in Books. When we try to Update the contact in Books, there is a json 1308 error.
I think the field for "Contact Name (Required)" is the problem. I am not sure why we have to add this field as the contact ID for the customer is already mapped above it in this step, so surely if the contact ID is populated, the update should go to the correct customer ID and the extra "Contact Name (Required)" field is redundant?
There are some other issues we have noticed. For example, where a Zoho Books customer does not exist and a new contact is created (the side of the router which does work), the fields for Books Custom Fields (final 2 screenshots) do not map correctly to the approriate fields in Zoho Books. For example the field for "Territory" is actually mapped by the field for "Code", and the field for "Customer Category" is actually mapped to "Shipping email"
Hope you can help out with this. It has me scratching my head!