[Gap while using custom support]

Printing a model which is big for my device if laying down, but fits when tilted.

It will fall without support, so I've dicided to add a custom supports at the center of a mass.

Added some. While printing I saw a gap between my support and a model.

Fixed this with some paper.

Next model - curra've added hole supports. I've added mine. My - with gaps, cura's OK.

Examined sliced - yep there is a gap.

So the question is how to use custom supports correctly.