I understand
why they may not want an empty guide section, I just don't understand why
now (the end of Nov 2018). It wasn't an error until EpubCheck 4.1. The wording of the 2.01 spec hasn't changed, so why, suddenly, has their interpretation of it? Sigil's created tons of epubs with empty guide items that all passed EpubCheck cleanly up until nearly the end of 2018. It doesn't make sense a lot of sense to me. But then, it clearly doesn't have to.