An example on at black profile could look like this:

Why: This problem is often seen at laptop containing a Nvidia Quadro M2000M graphic card.

Solutions

Go to ‘Object properties’ for the Vector theme. Go to ‘Profile’ and remove the tick in ‘Visible’ box.

Go to ‘Object properties’ for the Freeform File. Go to ‘Profile’ and remove the tick in ‘Visible’ box.

Go to ‘Object properties’ for the 2D models. Go to ‘Profile’ and place the tick at ‘Shows As Rectangle’.
Thereafter, go to ‘Geometry’ and place the dot at either ‘Fence Mode Squares. Not Mouse Clickable (fast)’ or ‘Cell Mode. Mouse Clickable (slow)’.