Missing history or background services stopped

As of Android 10 or so, Google has decided that apps which are not visible should be killed, regardless of whether they are showing a widget on launcher or running active services or excluded from battery optimizations.

This results in apps being killed, and often not allowed to restart even if those are excluded from OS optimizations.

In such situation you need to add a notification shorcut (app's settings, notifications, options at the bottom) to tell the OS the app is visible.

An alternative, some users confirmed working, is to add the overlay widget from app's overlay widget settings.