Running SW2016SP3ev...

Recently I'm having trouble with Smart Dimensions in part and assembly sketches. Often when I try to dimension the length of an "angled" line (neither horizontal nor vertical) I'll click the dimension along the length of the line, but then the Smart Dimension decides to do a Horizontal dimension (or Vertical) instead. This happens even if I right click to "lock" the dimension along the length of the line segment.

This happens every once in awhile.

Any thoughts - what am I doing wrong, or whatever?

thanks

marshall