Further testing has revealed the issue to lie with a LibreOffice grammar extension called LanguageTool.
This is a known issue in LanguageTool and removing the extension resolved the issue.
See this bug in the LangugeTool bug tracker: https://github.com/languagetool-org/languagetool/issues/1217?_pjax=%23js-repo-pjax-container
Further testing has revealed the issue to lie with a LibreOffice grammar extension called LanguageTool.
This is a known issue in LanguageTool and removing the extension resolved the issue.
See this bug in the LangugeTool bug tracker: https:/ /github. com/languagetoo l-org/languaget ool/issues/ 1217?_pjax= %23js-repo- pjax-container