Additionally my answer stated:
… and your text is set to one of these languages.
Text elements in Writer (paragraphs, words) can have different languages. Hence you need to assure that the text elements have the proper language settings. LibreOffice does not detect the language automatically. Example: If using a German environment (all LibreOffice settings being German (Germany)) and I’d like to correctly spellcheck an English paragraph, I need to set the paragraph to
English (US) or
If that does not work (and on my Manjaro that works), please upload a sample file, where you have errors and which won’t get marked as such.
Please do **not** use *Add Answer* but **(https://ask.libreoffice.org/t/spell-check-does-not-work/61778)** your original question to enhance the details of your question and/or to upload sample file(s) (answers are reserved for solutions to a problem on this Q&A site). Thanks in advance …