I have preloaded Office Home & Business 2019 and Windows 10. When I tried to open Word 2019 a couple of days ago, I got the message in the attached screenshot. I clicked on yes to disable the add-in. Since then, Word does not work properly. Among the problems, I can't open or save files from Word, delete or effectively rename the Normal template, use Options (clicking on it closes Word)
Have you tried full purge and performing fresh install?