Should hollow tiles be replaced?
Hollow sounding tile is not a defect per industry standards. If there is no resultant damages to the tile or grout, then I would just let it go. Make sure you have extra tile for the future just in case they do get damaged you can replace them.
Why does my tiles keep breaking?
If the cracking is a result of issues such as a cracked subfloor, incorrectly spaced joists, or protruding screw heads, these will have to be dealt with in addition to the cracked tile. Natural causes. Natural circumstances such as moisture penetration, pressure changes, or aging can also cause cracks.