I am having major issues in getting tools to run from the toolbox in version 3.2. In essence all but very simple algorithms like 'Split RGB' return errors and do not run. I cannot get any openCV or vigra tool to run. And I am not using the modeller. Just opening the tool and setting params does not work. The documentation seems to be in construction so it's hard to tell if I'm using this wrong or if there is a bug.
Before I start asking specific questions, do you need to install an OpenCV/vigra component in order to get these to run? Do the procesing tools from external sources (Grass and Saga) actually work or are they experimental? A classic error message I get is:
Error: select a library.
AttirbuteError: 'List' object has no attribute 'source'
EDIT: I noticed that the QGIS 3.2 installer setup Saga 2.3. But the OpenCV tools only appear in much later versions of SAGA. If you open the SAGA version installed by QGIS, there are no openCV tools. So I guess it's not surprising that when you run an OpenCV tool from the QGIS processing tools it cannot find its library. Is this worth an official bug report?