In macOS Catalina and later, you'll need to take an extra step to see window titles in Time Sink. This is due to a change Apple made that requires explicit user approval before Time Sink can see window titles. The only way we can get this approval from you is via a new built-in screen recording feature. Note you do not have to use this feature, but you have to enable it at least once to see window titles in Time Sink.

You'll find all the details on how to do that, for both the direct and App Store versions of Time Sink, in this blog post.