What happens when a production automation quietly breaks?

For people running n8n, Zapier, Make, Workato, or custom workflows:

Have you ever had a workflow show “successful” while the actual business process was broken?

For example:

• Data stopped reaching the CRM
• A webhook silently stopped firing
• A schema/API change broke part of the workflow
• A workflow stopped running without an obvious error

I’m trying to understand the real-world impact.

What was the most painful automation failure you’ve experienced?

Please share:
what broke → how you discovered it → how long it went unnoticed → how you fixed/prevented it.

And one important question:

If a tool could reliably detect these problems before you noticed them, would you actually pay for it? What would make it worth paying for?

I'm researching the problem, not selling anything.