How would you clean this tile?

[Dizzle Dazzle]

Hey so at my 9am this morning I was cleaning tile which was about 5 years old.
No matter what I threw at the grout it would not clean. In fact the parts of the tile which were dry looked like I barely hit them at all. Maybe the sealer somehow got in the way? How could I improve on this job?

 

[floorclean]

Try a little spot with some floor stripper

 

[PistolPete]

Try a little spot with some floor stripper

Or do a scrape test with a flat razor scraper.
Either one will reveal the dreaded mop n glo...

 

[DuckerTrucker]

Add some scouring powder with a little bit liquid and try to rub it. Does it help?