So, next bug :)

Draw circle with radius say 3. Now choose dimension->radius, select circle - dimension apperas with text R3 - ok. The same with dimension diameter and you will get 6. Now, open properties window, select both dimensions or one by one. Under "Primary UnitSystem" is positions "xn" - in both cases any change to this value is ignored and after laving field "1.0" is restored, so you cannot set scale for this this dimensions.

Next one: draw rectangle from 0,0 to 2,2. Select dimension->aligned, click on 0,0 and 2,2 -> dimension appears with text "2.8284" - ok. Now as above, go to properties, and try to change primary unitsystem "xn" to 0.5 - and... value in field upon leaving field is restored to 1.0, but dimension text shows "3.0"... Same bug in dimension->arc lenght

Linear dimension works as expected. Also, if selected more than one type of dimensions, "xn" dissapears from properties window, so you cannot scale them all at once. Tested on linux, V1.4,