Ink or Paper?

I had trouble with Platinum Carbon ink on my last outing. It was bleeding into my watercolour like mad. I thought it was the weather conditions, but no, I tried it at home again, with the same 3 pens I had with me, and the same bleeding/smudging happened.

This is on Hahnemuhle watercolour sketchbook.

Then I tried it in a different sketchbook, and there's almost no bleeding! This is on Etchr cold press sketchbook.

 Both behave the same way when I sketch of pre-painted surface, i.e. the line is much thicker. But I don't tend to do that much, so that's not too much of a problem for me.