That indeed works. I now have DayWeekBar English and Volume Locker running 'normally' again.
Just to clarify the steps I took following Svigir's advice:
Start the App in question.
Scroll down to and click Power saving.
Click Background power-intensive apps.
Locate the app in the list and click on the app icon.
Make sure all the switches are over to the right side of the screen (all On).