This happens when your low HFR, in this case is ~1.179. The maximum acceptable calculated final HFR for the validation frame is then 1.31. The dialog, in this case, is confusing because of rounding issues. The validation frame HFR probably had an HFR = 1.3156 and the max tolerance is 1.31. This will cause the warning dialog to appear.
To prevent this, I have rounded the HFR metrics prior to the comparison.
