Soft hyphenation doesn't render properly, but only at certain font sizes

[xavidotron]

Hello,

Not sure exactly what's going on, but I've found that sometimes when WeasyPrint breaks a word where a ­ character is, the hyphen is not rendered. But this seems to be dependent on font size, for example this example works correctly for me at 12pt but not at 11pt. Not sure if it's actually about the font size or some other quirk about the line length that's indirectly related to font size, or what.

See attached my example:

test.html

which renders for me as:

FWIW, I encounter the same bug when using hyphenate-character to change the hyphen that should be rendered to something else.