Add Back grid on some Excel cells

It looks like those two cells are merged. Select them and then choose Split from the ribbon.

They are not merged. I can clearly point to each cell respectively.

Any idea ?

I suspect they are formatted with a white fill.

Remove the fill and the grid lines will appear.

Thanks
Rob H

Rob's suggestion would have been my next guess. if not that, also check that they don't have a white border line.

I have attached my file here. Any idea ?
Sample.xlsx

Tks