“I have attempted to enable the Preview via the Office 365 Admin center. But the setting does not stick. I have included a video showing the issue. Basically I do the following:
1. Go to Office 365 Admin Center.
2. Select Settings-->Service Add Ins-->To Do Preview
3. Click the preview slider to on and click save
4. Click Close.
5. Click to check that the setting stuck and it has reverted to off.
Here is a video showing that:
Not sure how to resolve this.”