Some phones (among them Samsung, Huawei and Honor) kill background apps aggressively and keep Smarter Time from gathering the data it requires for your time analytics. We have very little control over how their processes work, but there are several workarounds. And don't worry, Smarter Time still won't use too much of your battery !
You will find below the specific settings for Samsung phones. Other phone manufacturers have similar settings pages to disable background task killing for specific apps. For Huawei and Honor phones they are in advanced settings > battery manager > protected apps. We will add more screenshots to the page as we get feedback for other problematic phones.
Keeping a notification displayed reduces the likeliness of the app to be killed.
Disable Samsung's automatic power saving for the app.
Then get rid of Samsung's battery optimizer for the app.