Hi
There is a good chance that the 711 you used is made by Miracle sealants but try Braxtons first. Give them a call and tell them you need to strip the 711 off some trav (you need an alkali stripper). They should be able to help if not try Miracle.
When you strip the sealer off there is a good chance it will clear some of the grout too. An visible grout while its wet with stripper us a window scraper or a stanley blade to take it off the suface.
That should do you, let us know how you get on
tiler