Arrowheads displaying as white instead of black

[Geoff]

Occasionally after adding solid fill black arrowheads to a line segment (Stroke format/select arrowhead), the arrowheads display as white with black outline instead of solid black. If I click on black fill, this sometimes restores the correct black color. Sometimes arrowheads revert back to white after this, and simply clicking on the arrowhead restores the correct black color. See attached screen capture jpg file showing arrowheads that were black in the dropdown arrowhead select menu. I am running Inkscape 0.92 on a Windows 10 laptop.