PDFBox PDPageContentstream.setTextMatrix() making text disappear

Question

I am converting POSPrint-data to a PDF. At one Point i need to strech the Text over 2 Lines, but with the width of the normal text. I'm trying to archive that like this:

CONTENT.beginText();
Matrix textMatrix = new Matrix();
textMatrix.scale(1f, 2f);
CONTENT.setTextMatrix(textMatrix);
CONTENT.newLineAtOffset(50, 50);
CONTENT.setCharacterSpacing(line.getLineSpacing());
CONTENT.showText(restOfLine);
CONTENT.endText();

sadly this results in the text not showing up at all. If i remove the lines for adding the textmatrix, or setting the matrix scale values to 1 this workes without any problem:

CONTENT.beginText();
Matrix textMatrix = new Matrix();
textMatrix.scale(1f, 1f);
CONTENT.setTextMatrix(textMatrix);
CONTENT.newLineAtOffset(50, 50);
CONTENT.setCharacterSpacing(line.getLineSpacing());
CONTENT.showText(restOfLine);
CONTENT.endText();

or

CONTENT.beginText();
CONTENT.newLineAtOffset(50, 50);
CONTENT.setCharacterSpacing(line.getLineSpacing());
CONTENT.showText(restOfLine);
CONTENT.endText();

Does anybody know why this happens?

I use PDFBox 2.0.25