Option to add 'Greek' is missing?

Today I added a paper written in Greek to my Calibre library. In the GUI, down in the Languages box, I tried to add 'Greek' as the default language of the paper. Instead I get an error message stating "The language Greek is not recognized."

I went to look for the the language in ISO 639 at the Library of Congress site to make sure I was using the correct syntax, but Greek is listed as "Greek, Modern (1453-)."

Previously this was the option listed but I can't find it now? Is this a bug? The only thing that shows up now is "Greek Sign Language."

I'm using Calibre, version 4.11.2

Please see the attached screenshots.

Attached Thumbnails