Also, this sounds like some kind of corporate or business communication, and these can often be best phrased in the passive voice, especially where an active phrasing could suggest finger-pointing or witch-hunting. Consider:
The monthly finance reports are not being correctly filed.
Someone (or some people) are not filing the monthly finance reports correctly.
You don't want to start a blame game or get people arguing. You just want the reports to be correctly filed.
Grammar and style checkers have the same weaknesses, in some ways, as sat-navs. You are driving the car, not the device. Consider its suggestions, but make up your own mind. Anyhow, you can go into Word's settings and select "grammar and style", or just "grammar", or turn off the checking altogether, or just the things you don't want it to whine about.