There are lots of problems with Opera it seems. My guess is that this is one of them.

I just hit this bug and can confirm. Steps to reproduce (using Opera 11.50 alpha):

1. http://musicbrainz.org/release/02de5b3e-56b8-4c30-b9ff-2d8303e601ca/edit
2. Remove the label "Cinepoly Records". Note that the input box stays green
3. Go to Edit Note
4. The Edit Note screen shows no edits, but still lets you enter an edit note. Submit the form.
5. No edit will be created and the label remains.

Public service announcement: if you ever fix an Opera-specific bug in MusicBrainz and you had to do something different in Opera from all other browsers, please let me know. I work for Opera and in this kind of situation it's probably a bug that we should fix, since clearly it's been breaking the most important site on the Web (MusicBrainz).

It's working for me now, see http://musicbrainz.org/release/df7226e8-8d88-4f5f-886d-8a7ba585fecb/edits

I'm still using 11.11, not 11.50 beta

On the test server, however, pressing the red x has no effect except that "#remove_label" is added to the URL. When I clear the label and cat fields, the edit note tab claims that I edited the label, not that I actually removed it. After submitting the edit, I get: http://test.musicbrainz.org/edit/14460078

HumHumXX, it sounds like you weren't using the same method I was. I've been trying to remove just the label, not the catalog number. Perhaps a workaround could be to remove both and then add the catalog number back.

Ah, yes, clearing the label field still doesn't work; pressing x now does. When I reported this bug, no method seemed to work, so there's progress!

It's still insufficient if you want to retain the cat#, of course.

The bug is not specific to Opera.

I confirm the same bug with Firefox 7.0.1 and Internet Explorer 9. I used the same procedure and got the same results as Philip Jägenstedt describes in the comment - 03/Jun/11 08:00 PM.

Removing both the label name and the catalogue number using the red cross works.

There are two separate issues here, and this is becoming very confusing.

Indeed clearing the label field in an attempt to remove the label does not work in any browser.

Since HumHumXX has confirmed that the red cross works in Opera now also; I will rephrase the bug to reflect current situation.

commit 1af42745dc28a2abaa5828610273d5edc13be25b