Make sure that BPM saving in tags is enabled in the program settings and click the Refresh button. If the problem persists, the problem is most likely with the ID3 tag format. Windows Explorer only supports the old ID3v2.3 tag format. Even in Windows 10 this situation has not been fixed and ID3v2.4 support has not been added. To fix this problem, you need a tag editor or use tuneXplorer, which allows you to convert tags automatically.