For test 13, that is working as it should, you are multiplying a scalar (unitless) by a length.
For test 14, that is a bit odd, however I suspect it is because they expect the numerator to always have units. The result is exactly as expected for 1m/1mm=Xmm if you consider the conversions done, ie 1m/0.001m=1000m * 1000=1 000 000mm.