The above question was posted last December by another person, and received only one very unhelpful reply, challenging his intelligence and offering no suggestion to actually solve the problem. I have the same problem: dictionaries are checked as present in Tools>Options>Language Settings>Writing Aids, but the spell check refuses to see them, saying “No dictionary available.” Don’t call me stupid, tell me what to do.
Edit: I found the answer myself: the line “HUNSPELL SPELLCHECKER” was not ticked. I don’t know who or what Hunspell is, have never seen it mentioned in Help, but “Spellchecker” was worth a shot in the dark, and that did it. I think of a Hun as a German, but what do I know?