QFontDialog sometimes incorrectly errors on setCurrentFont/getFont

Using QFontDialog, sometimes when setting current font (either via setCurrentFont or getFont,

an error is reported (application output in Qt Creator):

QFont::setPointSizeF: Point size <= 0 (0.000000), must be greater than 0

The font is created via:

QFont font;

font.fromString(QString("Nimbus Roman,36,-1,5,700,0,0,0,0,0,0,0,0,0,0,1")

Not all fonts fail, just some. The font string is obtained from an existing font via

font.toString()

QFontDialog does not select a font in this case even though the font family is selectable.