This is an annoyance that has been in place for a bunch of releases. The instance below is 2016 SP 4.0.
1. There's a point in a sketch.
2. The point is black (i.e. fully defined). I confirm by selecting the point--the PropertyManager indicates it is fully defined.
3. I don't want the point fully defined; I want to move the point.
4. I check for relations that could be defining the point or the line. SW lies to me and tells me there are none.
5. I delete the line and replace it.
6. I complain about it on the internet.