I setup Smart Lock with my home address and it worked great for couple weeks. One day it just stopped working. Smart lock on my Sony Xperia XA2 would just show white screen and no settings at all – no details. This is how I fixed it.

1. Go to Settings – Security & Location – Trust Agents
2. Disable Smart Lock (Google)
3. reboot the phone
4. Go to Settings – Security & Location – Trust Agents
5. enable Smart Lock (Google)
6. go back
7. click on Smart lock
8. and the problem is fixed