ParaView GUI needs is not clear about HTG array alignment.
The information panel shows the arrays as being point aligned, when they are closer to cell aligned. The colormap array choice, shows both point and cell aligned versions of each array, but the point one is not-functional. The spreadsheet view does not let you see any of the arrays. Meanwhile the .htg file format labels the arrays as being point aligned and the htg reader does not give you an option to choose from the available arrays to load.