Go in an open the Image Viewer for the Image Reader (this really is just a workflow containing some data to not have to look for some 3D data), select the one image in the table, and change to the ClearVolume tab: it's empty.
Tested with KNIME 3.6.2 and 3.7.1 and KNIME Image Processing - Clear Volume Integration 0.3.0.v201709290849.
It seems that some changes in ClearVolume have broke the integration with KNIME Image Processing (as brought up in https://forum.knime.com/t/clearvolume-not-showing-an-image/13513). I was able to reproduce the issue with the following workflow: ClearVolume.knwf.zip
Go in an open the Image Viewer for the Image Reader (this really is just a workflow containing some data to not have to look for some 3D data), select the one image in the table, and change to the ClearVolume tab: it's empty.
Tested with KNIME 3.6.2 and 3.7.1 and KNIME Image Processing - Clear Volume Integration 0.3.0.v201709290849.