It looks like the issue might be caused by how the formulas in N3 and M3 are referencing each other. This can sometimes cause Excel to behave inconsistently. Here’s what I suggest:

Simplify the formulas: Since N3 and M3 depend on each other, try breaking the logic up into separate helper columns. This way, you can keep the validation clearer and avoid circular references.

Check formatting: Double-check that N3, M3, and J3 are all formatted as numbers with 2 decimal places. Sometimes Excel gets picky with formatting, which could be causing the issue.

Test with simple cases: Once you make these changes, test a few simple examples like N3 = 4 and M3 = 4 to make sure the validation is working as expected.

Let me know if that works or if you need further help!