You're not using the autoDJ, so the metadata is being sent by whatever source client you're using (SAM Broadcaster, Edcast, the WinAmp DSP client, etc).
That's important for two reasons:
1) Centova Cast has no control over the format of the metadata string sent by your source, and
2) ShoutCast DNAS receives the metadata directly from your source and fires it off to your listeners without Centova Cast ever having had an opportunity to change it.
So in brief, no matter which way you cut it, this is not a Centova Cast issue. Since Centova Cast is not within the path of the metadata, it can logically only be a problem with either your source client or ShoutCast DNAS. ShoutCast DNAS is not known to munge metadata, so that leaves your source client as the only likely culprit.