I am not a tile professional but that does not look normal to me! At all.

The pros will pop up - just give them a little bit...

doesn't look like they were leveled

" Installed says it happens. Its normal. "

Let me guess he has been doing this this way for 30 years? It is normal only if you do not install them properrly. That is called lippage and there should not be any if done correctly.

Met with the tile supplier. She said it’s not correctly leveled and is talking with the installer this morning. Sigh. Hate to be that person but marble tile isn’t cheap.

Definitely lippage. The tiles were not installed level. This is usually the result of a poor installer, but sometimes it is the result of cheap/poor quality tiles that are not level/square and hard to level out by your average installer.

A tile leveling clip should have been used to make sure there was no lippage.

Hexes are 6x harder to set than squares. Marble hexes multiply that by 4 at least. So, marble hexes are 24x harder to set than a plain 12x12 tile.

And that^ is what happens when you have someone doing it wrong their whole career, and who refuses to use a lippage tuning system. That's a labor issue, not a product issue.