As a workaround until that's fixed, you can use Sigil to edit the epub and do a global search and replace of
for
and hopefully that'll fix the conversion issue for that epub. (Sigil can search and replace in "all HTML files", so that should be just a single operation per epub - hopefully not too onerous)
I'm not as familiar with the part of FFDL that actually generates the epub file as I am with the metadata adapters, but if Jimm doesn't beat me to it I'll take a look when I get back home this evening and maybe see if I can figure out that problem.