Originally Posted by Modmike
I would contact FR ASAP. They may know exactly what it is and have a solution.
Your last option is muratic acid., available at most home improvement stores. I think it's the only thing that can clean set grout or haze, if that is what it is. It will not damage tile but is extremely caustic so be sure to use rubber gloves and follow instructions.
Thanks, Modmike. I just reached out to FR and hope to hear back shortly. We are very upset with the dealer - the first we would have done (and the first thing we told the dealer to do) was to contact FR. The fact they waited nearly 2 weeks before contacting them is inexcusable. How do you fix it if you don't know what it is?
As for muratic acid, we thought about that, but figured it was not our problem to solve.