Cannot extract centroids after Surface|Curve

Hey,

I'd be very grateful for help, description of a problem below.

What I created:

1. Hexagonal grid

2. Surface defied by polyline with holes (defied by curves)

Goal:

Have only those cells within the surface which are fully inside it(each cell's area should be 100% inside surface).

Idea how to do this:

Use Surface|Curve to cut the grid of cells to the surface --->

---> Area to get centroids of those cells --->

---> Dispatch using as pattern distances of cells' centroids from polyline to have in one of list those that are fully within the surface --->

---> Dispatch using as pattern distances of cells' centroids from curves (that defy holes) to have in one of list those that are fully within the surface

Problem:

Cannot use Area to extract centroids. Ironically, when I click on the Area button is shows me centroids of all of cells that are fully inside surface but button is red so I cannot progress.

I tried using Split Surface too (instead of Surface|Curve) but it crashed my PC, even after flattening input data.

I'm a newbie and looked for answer but did not manage to find topic that would relate to my problem. Maybe I formulate my questions in wrong way.