Two things, both of which are likely contributing to this not working. First of all, you're trying to boolean planar surfaces. Any boolean operation needs a clearly defined inside and outside volume to determine what surfaces to keep/remove. Since these are planar, this is likely messing up that logic. Secondly, it looks like your trying to trim out tangent (or nearly tangent) circles. This is something that the Rhino intersector is notoriously sub par at, so you're not likely to have much luck with booleaning those, even if the volume issue described above is resolved.
For tangency cases, I´d rather use difference between regions not solids, and then "solidify" the output regions to get the final Breps. It works not only in tangencial cases but also in overlapped-curves cases. See image.