Why is make a tab not showing up in the tabs?

Hi @Brady, Scott

Good day! Welcome to Q&A forum!  

Thank you for reaching out. To better understand your issue, please clarify the following questions: 

1. Is the channel Standard, Private, or Shared? 
2. Where is the file stored: in the channel’s Files tab (SharePoint) or in OneDrive/another site? 
3. Are you a Team Owner, and do other members experience the same issue? 
4. Which Teams client are you using, desktop (classic or new), web, or mobile? 
5. Do you see any error message when you try to add the tab? A screenshot would be helpful. 
6. What steps did you take to make a file a tab? Did you follow the steps via Tips for Teams files - Microsoft Support ? 

After following the steps in the article, try making the file as a tab at https://teams.microsoft.com. If it works there, kindly clear the desktop cache and restart Teams. 

Moreover, please have the confirmation from your Admin that tab apps (Word, Excel, PowerPoint, PDF Viewer) are allowed in the Teams Admin Center under Manage apps and Permission policies. 

Your confirmation is very important. Looking forward to your update. 

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