I'm not sure your Word is up-to-date. I am showing Version 1908, not 1808.
That is not the issue, here, though.



Is your document in compatibility mode?
Assume, for the moment, that there is such a limit. If so, you can work around it by spell-checking excerpts from your document.

In the future, please crop or shrink your images. Very wide images makes posts difficult to read.