Here are two screenshots of roughly the same area, where I use the Minimum Distance algorithm to first produce a preview and then by pressing the RUN button in the Classification tool as shown in https://semiautomaticclassificationmanual.readthedocs.io/en/latest/tutorial_1.html.
This happens with all algorithms, it seems to prominently class everything as buildings.
The preview

The output .tif

Could this be due to the same band stacking issue as in #416 ?