Laying the tile on wood or a cement pad?
If your subfloor is solid I’d throw down
https://www.schluter.ca/schluter-ca/...-(DITRA)/c/M-U a membrane and use outdoor tile.
Then it could be okay.
Seems like the problems arise when the floor moves so isn’t solid. There is moisture wicking up to the grout and tile. When the tiles are the more porous indoor tiles.
Like one mentioned tiles are used around outdoor pools but there are different types of tiles and applications thereof.
But I’m far from an expert.