Hello Mr S,
Here is my understanding of why Mp3tag shows the number of stars for certain players.
There is no accepted standard or convention for the numerical values within the 0 to 255 rating range, nor is there a standard for the allowed number of rating stars. Some players even allow half stars. Such variants create a problem when Mp3Tag attempts to display a rating value because no single display formula can accurately show the number of stars intended by the player. In addition, editing raw values can be confusing and prone to errors for users who do not understand these variations.
Therefore, Mp3tag added special "extended" rating fields for a few popular players. These fields use the e-mail signature in the POPM tag to identify the player that wrote the rating and to return a number corresponding to the number of stars as shown within that player. Originally, there were just two such rating fields, for Windows Media Player and Media Monkey. Mp3tag v. 2.48 added one for Winamp. As you found, as of v. 2.49 raw POPM data for those players (only) no longer displays.
However, when you rate and save a file in Mp3tag by using the new Winamp rating field, that number is correctly saved as a Winamp POPM value and my tests show that the file does show the correct number of stars when played in Winamp 5.62. So, with Winamp files, I no longer see a need to work with the raw POPM data. And, as far as I see, the popularimeter tag works just as before in Mp3tag for all players other than the three mentioned above.
I prefer to show ratings as "stars" in column view in Mp3tag, using a script that I posted on April 12th. Scroll down to the eighth post in the thread for the current version of the script:
Column Script to Show All POPM Ratings as "Stars"
Doug Mackie, aka Retroman in the Winamp forums