Workflow doesn't detect update from custom function

Workflow doesn't detect update from custom function

Hi,

I am trying to apply a tag to a Contact based on a field that is updated through a function that captures data from a custom module.

I created this workflow but nothing is happening. It looks like Zoho doesn’t know that the Contact is edited when the custom function updates the field “Last Ride date”.

The workflow works fine when I edit any field and save the Contact. But that won’t work for me. I need this action (apply the tag) to be automatic.

What can I do?

Thank you,