If you've created a Process Builder that fires on a Task and uses a Messaging Template, and that Messaging Template contains Merge Fields, those Merge Field will not update with the corresponding values. It sends the Message to the Messaging User's device from the Account or Contact, but won't pull in the merge fields as you may expect.
The error received in the Messaging Error Log is:
"Can't insert the merge fields into the message because Quick Text isn't supported on the object you specified in the process. Messaging sends the message without the merge fields. Re-create the process using an object that supports Quick Text. Or re-write the message without the merge fields."
Task is a standard object that has a child relationship to both Account and Contacts.
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