Ektar 100 is both contrasty and oriented toward colour saturation.

And in real life, shadows often are a bit blue (open shade lighting).

So Ektar tends to make the blueness of shadows quite obvious.

It isn't really crossover - instead it is just accentuating the situation when scenes are receiving illumination from multiple sources.

If you expose Ektar 100 in the studio with controlled lighting, you won't see blue shadows.