Workflow error handling configuration : Global error handler not triggered on query failure?

We have a workflow that takes a payload from an incoming REST call, and uses it to trigger several GET and POST queries.

We detected that one of these queries within the workflow was occasionally failing,
so we're trying to get some error reporting implemented using the techniques described here:

Specifically, attaching the 'Global error handler" to a JS block that triggers a reporting query.

This reporting query works when manually triggered, but when I actuate a "real" failure using a bad input payload, it does not trigger the reporting query attached to the "Global error handler" as expected.

So, a few questions:

  1. Do I correctly understand that the "Global error handler" should fire when a GET contained within the workflow fails?

  2. Are there any additional config steps required for the "Global Error Handler,": beyond attaching it to a viable block type as shown in the docs?

  3. Is there another way to add a failure condition handler to a REST query within a workflow?

Thanks for reading, all guidance is appreciated!