I prefer Oxy Blaster from Magic Wand as my Alk cleaner.
and despite what lazy cleaners tell you, scrubbing helps a lot.
and check to see if the grout has a topical sealer on it.
You find that home owner love to put clear coats down intentionally and unintentionally.
Mop n Glow is the debil
If your acid cleaner is not making the grout fizz, clean the floor with a stripper first ( may take 2 or 3 times to get it all off)