I'm having issues with markers in 2018 SP3 on Windows 10.  In old versions, markers drew perpendicular to tangent of the line they were marking at the REAR of the arrow (IE, how you would expect an arrow to be drawn.  In 2018 SP3, the behavior has changed and now draws perpendicular to the tangent at the NOSE of the arrow, resulting (especially when using the freehand tool) for the arrow head to be misaligned badly (ie, having the arrow hanging off the line by its nose.)  Anyone else having this