Spell Check not working in Word 365 after automatic update

In Word, a filled check box means that the selection contains conflicting settings. For example, if a selection includes some text characters for which "Do not check spelling or grammar" has been activated and other characters for which "Do not check spelling or grammar" is turned off, you would see a filled check box. 

However, it turns out that for any selection large enough, you will always see a filled check box, even if there is no conflict.

In other words, it isn't very likely that the option gets activated automatically. If that is indeed happening, the usual culprit would be a poorly designed add-in.

This happens to me as well.  Spell check does not work.  Tried every fix going, every suggestion made.  Spent hours on this problem.  Absolutely no success whatsoever.  I pay for Office 365 every year, so why isn't this bug fixed?  If Microsoft can no longer offer this spell check and grammar facility on Word they should say so.  If not then fix this bug please.

"This is to tests the grammars mistakes in these sentence to see if their fixes."

Grammar checking finds ZERO grammar errors in the above sentence.  This is inexcusable.  This issue popped up months ago and not only has it NOT been fixed, it hasn't even been acknowledged as a bug.   100% inexcusable.  And finding no grammar errors in the above sentence is embarrassing.    Here's a suggestion:  REMOVE GRAMMAR CHECKER.  Better to have no grammar checker than to have one that doesn't work.  And seriously, Microsoft created the bug with an update when they changed the Editor, you mean to tell me they can't fix it?  This is beyond ridiculous.

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This is certainly not something I manually changed. There is the potential that it happened after editing and saving a Word document in another language. Otherwise, I'm guessing it happened after an Office 365 update.  Any idea how/why this would be automatically changed?

The thing that makes this seem so perplexing is that the setting to not check spelling or grammar is a character-level setting, not a document setting or a setting for Word as a whole. If text with this setting is copied and pasted, it can carry the characteristic with it.

Mastering the Spelling Checker by Suzanne Barnhill, MVP

"This is to tests the grammars mistakes in these sentence to see if their fixes."

Grammar checking finds ZERO grammar errors in the above sentence.  This is inexcusable.  This issue popped up months ago and not only has it NOT been fixed, it hasn't even been acknowledged as a bug.   100% inexcusable.  And finding no grammar errors in the above sentence is embarrassing.    Here's a suggestion:  REMOVE GRAMMAR CHECKER.  Better to have no grammar checker than to have one that doesn't work.  And seriously, Microsoft created the bug with an update when they changed the Editor, you mean to tell me they can't fix it?  This is beyond ridiculous.

Did you look to see if you have grammar checking for this sentence turned off?

Put your insertion point in the sentence, i.e. in the word "their." and press Shift+F1.

What do you see about the language setting?