Futurism +100 tourism bouns doesn't work?

Well, either my understanding of the ideology is broken or the bonus code is broken

I chose futurism which should give me a +100 tourism bonus with every civilization I know whenever a great artist/musician/writer is born but a few of them have been born since and I didn't get any bonuses.

What's up with that?

Where do you expect to see it? It's a one time bonus, it doesn't show up on the top panel where your per turn generation is listed.

You need to go to the culture screen and there to the last tab (Influence by player) and then mouseover your tourism progress towards a civ to have your total accumulated culture towards them being displayed. That definitely should have increased by 100 for Futurism each time a GWAM was born.