Not sure Kevin something solvent based anyway
You always use a High Alkaline first possibly coupled with honing powder if required. This gives you a chemical clean & stripper coupled with a mechanical strip. Now you haver said you tried Lithofin Wax Off and that didn't work. So you just don't jump in with solvents as there are other considerations. My advice is to try progressively stronger products so in our range I would try progressively
1. Miracle Finish Sealer Stripper
2. Miracle Residue Remover
3. Miracle Epoxy Grout Film Remover
and then finally if they all fail Miracle Mira Strip. I would also couple all the above with honing powder.
Kevin