Google LTI - No Preview Available

[lennyheidt]

Using Google LTI as an external tool. Canvas recognizes students' submissions. However, it does not provide a Preview of the submission or grading availability.
What steps should I follow in order to be able to see the document in the PREVIEW? 

Not quite what was promised. 

https://community.canvaslms.com/t5/The-Canvas-tl-dr/New-Meet-Google-Assignments-LTI/ba-p/388622