Review on 🎨 Ivory Grout Pen Tile Paint Marker: Waterproof Grout Colorant and Sealer Pen - Ivory, Narrow 5mm Tip (7mL) by Kenneth Foster

I have purchased several of these grout pencils and have used them with great success. I've used them on floor tiles before. This time I wanted to restore the grout on the bathroom tiles. In my opinion these grips do not work well with tiles. Literally after a few squares, the pen stopped working. I kept shaking it but the color didn't fill the tip. I tried the second one, thinking the first one was defective, but the same thing happened. Also, the ivory color was lighter than the color on the lid. Disappointed but maybe try again soon. Please advise. Not clean. When these pins work, they cover well.