If you have issues with the scan never finishing you can start strawberry from the terminal to get an idea where it's stuck. Similar problem reported on GitHub turned out to be a permission issue: https://github.com/strawberrymusicplayer/strawberry/issues/583
If you are on Linux or macOS can simply open a terminal window, then start strawberry by simply typing strawberry on Linux. On macOS you can type: /Applications/strawberry.app/Contents/MacOS/strawberry
On Windows you have to use the debug version to see the output.