I have the exact same problem.

In my case I have removed all the loose tiles (about 2 five gal. buckets full) and have cleaned them with acid. They look brand new and are ready to be applied.

Now I just need to find a good thin-set compound so I can attach them and then grout. But I am not sure what are recommended products to use for pools and what I need to do to prepare the concrete for the thin-set.

Hopefully someone replying to your post will help.

Thanks
Frank