Created attachment 172649 [details] Screencast Right click a misspelled word and choose Ignore. Make an edit elsewhere in the document. The word will be squiggly-underlined again.
You need to select "Ignore All" (means "All" occurrences of the word for the whole session) instead of "Ignore" (means "once" for the current edit). From my perspective not a bug.
I agree with Uwe, closed as NotABug