FLAC tags compromised in Ubuntu

I'm using MP3Tag to get the publisher and year for FLAC files used for a Linux radio station, a necessary prereq for net streaming. The audio files were ripped with Soundjuicer and tagged, somewhat, with Musicbrainz.

When I add the other data (using MP3Tag in Wine) everything seems to go smoothly, except that Rivendell (Radio Automation Software) can no longer recognize the original metadata. I'd love to do all my tagging with MP3Tag because it's the best (yes, I even donated!) but is there something specific to FLAC or Ubuntu I'm overlooking here?

It's not a Wine issue, because Puddletag and Picard are doing the same thing.

I guess it boils down to this: what is different about the way the tagging programs attach metadata than the way it is originally attached by, say, Soundjuicer (which though incomplete, uses the same database as Picard)? Is the file name being changed, and if so, how does that even matter?

If anyone could shed light i'd be most indebted...

You could check what types of tags are read by the various programs.
So have a check whether there are APE, V1 and/or V2 tags in the files.
It could be that you read some tags but write others. And as APE overrules V1&2 it could be that you see what has been read (APE) but not what has been written ...
You see the tag-types if you open the extended tags dialogue for one file and have a look at the window title.
Also, you could check the mp3tag settings in Tools>Options>Mpeg

thanks for the suggestions--tried everything but nothing is working, at least as far as adding record label and year to other metadata. it works, but only by making the other data unrecognizable.

my last name, ohlweiler, is supposedly from northern germany, but i've never been there...

What do you mean by that?
What have your tried? Checked? What was the result?
Do you have APE tags in your files?
What have you done with the findings?
Have you deleted tag types so that you end up with V1&V2 tags only or APE tags only?

i tried every concieveable combination of checking and unchecking boxes in a series of tests and even methodically wrote down what i did in each one, but none of them worked.

No surprise as none of these options have any effects on flac files.