My tags are truncated to 30 characters in Windows Media Player!

Windows Media Player (WMP) can only read ID3v2.3 tags. If you have tagged your files with ID3v2.4 WMP falls back to ID3v1 which has a limitation of 30 characters per title. Writing ID3v2.3 is the default, but you can configure it in the tag options for ID3.

Prior to version 0.14, Picard’s default setting was to write ID3v2.4 to files.