Spell Check is hinkie

I’ve noticed that Writer doesn’t keep all the decisions I make. Telling Writer to “Add to dictionary” is not always accepted. I frequently find that I have to redo later. I suppose this might be related to the fact that I can’t get the “Help>LibreOffice Help” option to work. I still get the popup message that says “The LibreOffice built-in help for current UI language (English (USA)) is not installed on your computer.” But it’s frustrating all the same. I have tried to download the offline help module from LO, but that doesn’t work either.