Search a share point document library within teams

[ipconfig_28]

We have just created a new team and plan on using teams throughout the company. We uploaded a mass amount of files into a SP document library and added it as a tab in teams. The issue is we cannot figure out how to search it? When we search it and select the team no files come up. Even if we write in the exact file name. 

[#2]

Is the Document Library with all the content part of a different SharePoint site than the Microsoft Teams team you have added the tab to?

If so, then when searching within the Teams app results will not be returned from this library. The Teams app only returns file results from SharePoint sites that exist to support a Microsoft Teams team (every Team you create has an associated SharePoint site to manage that teams channel files).

A few suggestions:
People search for files via the Office.com or SharePoint start page
Create a Team for the SharePoint site hosting the content, or move the content into a Team.

[#3]

@James Mallalieu This was a site that was create when the Team was created. 

Thats why im having a hard time understanding why search will not work.

[#4]

Try this, go to a channel in the team, select the files tab then "open in SharePoint". Go to the home page of the SharePoint site and perform a search.

If your files are not returned, go to the document library containing the files and check the following via the library settings option (via the cog):
1) Manage files with no checked in version - Ensure your files have been checked in
2) Advanced settings>Allow items from this document library to appear in search results - should be set to Yes