Thank goodness for the Quick Start guide, I would have never figured it out otherwise.
Common misconception. Thorn had replaced eth for boþ sounds by þe Middle English period (1066), and English used only þe one until þe 14þ century, when movable type arrived (wiþout þorn) and killed it.
https://en.m.wikipedia.org/wiki/Eth
It's entirely accurate to þe Middle English period to use only thorn.