Worktime acts in the background when it is not actively used, and is designed to run for as long the device is on. It is designed with the stock "Google version" Android in mind. However, some manufacturers have implemented their own battery saving methods that stop Worktime unexpectedly. Or, you may have an additional "battery saving" app installed that stops other apps. Adding Worktime to the list of "whitelisted" apps might help it work.
Here are some ideas of what to try, but first of all, if you haven't opened Worktime since restarting your phone, try to do so and see if that helps.
Huawei
Go to Settings > Advanced settings > Battery manager > Protected apps
Make sure Worktime is among the list of protected apps.
Lenovo
There are two settings on the LG phones that might affect Worktime.
1. Go to Settings > Background app management
Make sure that Worktime is unchecked.
2. Go to Settings > Applications, open Worktime
Make sure that Restrict to launch is unchecked.
Xiaomi/MIUI
Here are some ideas of what to try, but first of all, if you haven't opened Worktime since restarting your phone, try to do so and see if that helps.
Huawei
Go to Settings > Advanced settings > Battery manager > Protected apps
Make sure Worktime is among the list of protected apps.
Lenovo
There are two settings on the LG phones that might affect Worktime.
1. Go to Settings > Background app management
Make sure that Worktime is unchecked.
2. Go to Settings > Applications, open Worktime
Make sure that Restrict to launch is unchecked.
Xiaomi/MIUI
Other phones
If you have a phone that is not on this list, please share your experience!