Fix a spreadsheet formula that shows an error or the wrong result

App and version: {{app_and_version}}
The formula, copied exactly, and the cell it is in: {{formula}}
What it shows: {{what_it_shows}}
What it should show, and how I know: {{expected_result}}
Who relies on this sheet: {{who_uses_it}}

The cells the formula refers to, with a few sample rows (headers, values as they appear, and any rows I suspect):
"""
{{sample_data}}
"""

Task:
Find out why the formula above gives the wrong result in {{app_and_version}} and give me a fixed version, so that I can repair a sheet {{who_uses_it}} rely on. I want the cause explained, not just a new formula, so I can spot the same problem next time.

Format:
1. Most likely cause: one or two sentences pointing to the part of the formula or the cell responsible.
2. Other possible causes, most likely first, each with a quick test in the sheet to rule it in or out. Common ones: numbers or dates stored as text, extra spaces, a range that misses some rows, a reference that shifted when copied (missing $ signs), an exact or approximate match setting, cells blocking a spill, or a function this version does not have.
3. The fixed formula in a code block, ready to paste, changed as little as possible.
4. What changed: each change in one plain sentence.
5. Check it: two or three of my sample rows with the result the fixed formula should give, worked out by hand, so I can compare.

Requirements:
- Under 350 words, plus the formula.
- Use only functions available in {{app_and_version}}.
- Do not wrap the formula in IFERROR to hide the error unless the error is expected for some rows, and say why if you do. A hidden error leaves a wrong number in place.
- If the fix needs the data cleaned (for example text converted to numbers), give that step separately rather than burying it in the formula.

Example of one check row's form only: "Row 4: ID 1042 is in the price list, so the fixed formula returns 18.50."

If my sample does not show the problem, say what else to paste, for example the cell's number format or the first rows of the lookup table.