In macOS Mojave some applications will require you to allow Memory Tracker to control them in order for it to be able to read the window title. 

You'll get a popup that looks like this, and you need to hit "OK" in order for Memory's tracking to continue to work:

If you by mistake hit "Don't Allow" you can remedy this by going to System Preferences -> Security & Privacy:

Then click "Automation" in the left pane, and check the unchecked applications under "Memory Tracker by Timely": 

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