I have a similar problem. I use Audiocatalyst which uses the Xing encoder. For some reason it doesn't put the VBR jump offsets in at all. VBRFix thinks that the files are fine and won't try and fix them though because it detects the Xing header.

The only way I have found so far is to MP3 Tag Studio, but it will only do one directory at a time. i.e. it won't do things recursively. So for every CD I rip I then have to run it through MP3 Tag Studio before uploading.

Does anyone else have this problem with Xing/Audiocatalyst?