So, this is a weird one. If I start a new document in Writer, and I’m writing in a pre-installed font (like Times New Roman on a Windows machine or Liberation Serif on a Linux machine), if I type a nonsense word like dsfhfiou, it’ll get automatic red squiggles through it, because that’s how real-time spell check works. But I installed a weird font called 18th Century Kurrant, and if I switch in the second sentence to that font and type dfhfijofd, no red squiggle shows up. If I switch back to the pre-installed font, the spell check again works fine.
Really not sure what’s going on here, or if something needs reinstalling. What I can say is fortunately, if I actually click “spell check,” the long-form non-instant checker does catch the misspelled words. So… maybe a bug? Maybe just weirdness with one font? Honestly don’t know. But there you go.