Possible hacking of my OnePlus6. Contacts disappearing under 'Speed dial' The speed dial section in my One Plus 6, until now had a list of contacts who I used to call recently and/or contacts who I used to call on a frequent basis, never used to be a speed dial contact that I had manually added. 

But now, all of a sudden, it's empty.
What can be the reason? Is there a good chance my phone is hacked?

Can someone please me
I doubt that your phone has been hacked. There have been other people complaining about the same problem has shown in the OnePlus Forum and even here. It must be a problem with the app itself. One simple solution will be to use another Phone app. Or if there is an update to the OS or Phone app, then update it to the latest version and check if the problem persists.