I have been right-clicking red underlined text and adding to dictionary every time I bring up a topic for edit. When I save and leave a topic and then come back to it later there are the same text that is red underlined and I will once again add to the dictionary (below). How can I make Add to Dictionary stick?
I can see that is 2019 but not which update you have applied. Check you have the latest update (5).
Add to Dictionary is working for me.
See www.grainge.org for free RoboHelp and Authoring information.
Maybe it is working.