finding a lost file created in a third party app

I exported a file from Microsoft word into a third party word processing app - ‘only office documents’ is the name of the app, downloaded from the App Store. This morning I realized a file I have been working on all week is now missing, and searching for it within that app gets me nowhere. Is that file gone for good now? It should have been saved to my IPad directly, not to the cloud or another app like Google Drive, so I’m not sure why all of a sudden this particular file is gone from the app’s opening page while the other six remain.

Any ideas would be helpful, I will be so upset if I’ve lost a week’s worth of work.