Here's how to troubleshoot data validation issues related to hidden cell references in Excel:

1. Identify Hidden Cells:

* Unhide Rows and Columns: The first step is to check if the referenced cells are simply hidden. Go to the "Home" tab and click "Format" in the Cells group. In the dropdown menu, choose "Unhide Rows" or "Unhide Columns" depending on where you suspect the hidden cell might be.

2. Check Sheet Visibility:

* Unhide Sheets: Ensure the sheet containing the referenced cell isn't hidden entirely. Go to the sheet tabs at the bottom of the window. Right-click on any visible sheet tab and select "Unhide" to display a list of hidden sheets. Choose the relevant sheet to unhide it.

3. Review Formula References:

* Examine Formula: Open the cell with the data validation issue. Double-click the cell to see the formula in the formula bar. Analyze the references used in the formula. Look for any cell addresses that might be hidden.

4. Use "Show Formulas":

* View All Formulas: On the "Formulas" tab, click the "Show Formulas" button in the Formula Auditing group. This will highlight all formulas in your sheet, making it easier to spot hidden cell references within the formulas.

5. Check for Broken References:

* Error Messages: If the referenced cell is deleted or moved to a different location, you might encounter an error message like "#REF!" in the cell with data validation. This indicates a broken reference.

6. Fix Broken References:

* Adjust Formula: If you find a broken reference, you'll need to adjust the formula in the data validation rule. You can either:
- Manually locate the new position of the referenced cell and update the formula accordingly.
- Use relative references (e.g., A1 instead of $A$1) to make the formula more adaptable to changes in the sheet structure.

7. Consider Named Ranges:

* Use Named Ranges: If you frequently reference hidden cells, consider creating a named range for them. This makes the formula easier to understand and less prone to breaking if the cell is hidden or moved.

8. Utilize Error Checking Tools:

* Error Checking: On the "Data" tab, click "Data Validation" and then "Error Checking." This tool can help identify potential issues with your data validation rules, including broken references.

By following these steps, you should be able to identify and fix data validation issues caused by hidden cell references.