Document grayed out after opening and closing.

I opened a document in Word for Mac version 16.84. When I tried to close it, it asked if I wanted to save the changes. I hadn't made any changes, but I clicked YES. When I tried to open it again, it was grayed out in the directory. I then opened it from "Open recent," and I newly saved it, replacing the other. Still, in the directory, it's grayed out, even though I originally created it in Word years ago. Could it be because it's old and in a format that Word no longer uses? If so, why didn't it tell me that?