In the pcl-1.9.1 release, the SampleConsensus line model is broken. It is fixed by https://github.com/PointCloudLibrary/pcl/commit/36c2bd6209f87dc7c6f56e2c0314e19f9cab95ec.
I suspect they won't bother doing a bugfix release anytime soon, so it'll probably be left to the distros to apply that patch.
Created attachment 593968 [details, diff]
patch that fixes pcl::SampleConsensusModelLine
Our tests (on Fedora) have shown that the patch works btw: https://github.com/fawkesrobotics/fawkes/issues/174