Website Feature Logic Fix

My site is live but one key feature is misbehaving. The problem is purely functional—something in the underlying logic is off—so I need a developer who can dive into the code, trace the flow, and restore the expected behaviour.

Here is what I know so far:
• The visual layout is fine; the issue lies in how the feature executes after a user action.
• Errors surface only under certain conditions, so replicating and unit-testing will be essential.

What I need from you:
1. Analyse the existing codebase, pinpoint the faulty logic, and explain the root cause.
2. Implement a clean, maintainable fix without breaking neighbouring components.
3. Verify the solution with thorough testing (manual plus automated if you prefer).
4. Hand over a short summary of changes so future updates remain straightforward.

Stack is a typical LAMP setup with a few JavaScript modules on the front end; please be comfortable moving between front- and back-end layers as needed. If this sounds like your kind of debugging challenge, let me know your approach and estimated turnaround time so we can get started right away.