When you work with linework and you need to add an arc in between two angled segments and for some reason the fillet command does not do it because of the direction of the segments, then you are forced to use the circle and the option for tangent tangent radius, a.k.a. ttr. Working with this for lots of times, it happened that the circle that was supposed to be tangent to the two elements, sometimes was not to one of the elements.
The issue seems to have to do with working in geographic coordinates that have large number values for x & y. Since in the civil engineering world we are using those on a daily basis, then we would most likely have this issue. When you have this issue, just move the elements that you need to add the arc (circle) in between to somewhere around 0,0 and you will not have the issue in making the circle to be tangent to both elements. Once you’re done, just move them back.