As I wrote here, Smart Lock works perfectly for me. It doesn't work for you, and you'll wait for Google to fix it so that it always works for everyone in various conditions. However, when it will do is a question, because Google did not correct some of its issues even after 10 years ...
At the same time, clearing caches does not cost you anything at all, you will not lose anything, you will do it yourself and you do not have to wait for anyone. Then restart for sure and see if it helped. It won't take more than 2 minutes, I think it's worth a try.
