Searching for file contents in Microsoft Office files does not return any results.
If the search does not return any results, but te search filter have been set corretcly, this could be due to a missing file content reader for Microsoft Office files. The reason for the absence of these handlers is in most cases a non-existent Office installation.
If you do not want to install Office on your system, Microsoft provides separate filter packs to install these file handlers. These can be downloaded here: https://www.microsoft.com/de-de/download/details.aspx?id=17062