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