I checked proofing settings and looks OK, asked to re-check spelling and word could still not recognize misspelled word. I have Windows 10 with Office365.
spell check does not work in all languages I use so it's not a specific dictionary that is not working.

Select a misspelled word. Check the Review>Language setting for that word.

Mastering the Spelling Checker

This is a character-by-character setting, not a document-wide or system setting.

thanks Charles, I did as you advised and I found nothing wrong, English is enabled and so are the proofing tools.

Any chance the misspelled word has been erroneously added to your custom spelling dictionary?

No, sure not. It's not one or two words, it's the whole document (50 pages). When I ask to re-check selling and grammar I immediately receive a message that spell-check is over and I'm good to go.

Go to a misspelled word.
Click in it or select it.
Then press Shift+F1 to reveal formatting. Do you see anything about not checking?

Attached Images

00 deleteme 1.png (21.4 KB, 15 views)

thanks, that worked! I remember doing it before but this time I clicked the button which sets the preferences as default.