mkok, after you verified that WAV tagging is enabled, you can apply the tags to your old files by doing the following:
1. select the files
2. right-click the selected files > Library Tools > Update Tags (from library)
Try this first with a few files to get an impression of the tagging speed. If you have thousands of big WAV files tag writing may take a while.
Keep in mind that only very few other programs support WAV tags.