A long-running data sync job wasn’t working. It ran at the time it supposed to, and it completed successfully. However, when you checked the reports, the numbers didn’t match.
This type of problems will put your dev team in a “firefighting” mode, dropping everything they were working. Debugging such a complex bug will take hours; validating the fixes more hours. In my story, it took five days of two engineers.
Let’s say you were paying $100k/y to each engineer, that’s around $4.1k total cost to fix the problem. Would you spend another $4.1k to measure the fix ROI?
You can argue that the data sync job was poorly designed, or it wasn’t set up correctly. If you have spent that $4.1k upfront to get it right, then it would’ve been easier to see it as an investment, rather than a sunk cost.
Stop looking for ROI on bug fixes. Every dollar you put in your tech will have an ROI; it is just the cost of measuring it might be too high to bother about it. Set a “bug fixes” budget aside, and spend 50% of it during the design and testing phases.