Tagging "Label"

[Classpro]

I'm trying to include a "Label" tag for the publisher of the album. I actually put the tag under "Publisher" and I added "Label" to the minimserver options. The "Label" shows up and has some of the albums sorted by the label tag, but many others are showing up as [unknown] even though they appear to have the identical tags. I have tried to find something in the album tagging that that might be conflicting for the ones that don't show up, but I don't see any differences between the ones that do show up and the ones that don't. Also, there are no errors showing up in the log. Is there a solution?