I've been cleaning up tags in my classical library and have discovered a bug. At first I thought I had been careless and going too quickly and wiped out all the tags for a field on every track. Literally 1000's. Fortunately everything is backed up. As it happens, it wasn't me that made the mistake. Or at least I don't think it was. This morning I had been editing tags in the title field for a while and found one I wanted to change in the album field. I selected the tracks, selected Properties, in the context menu for Album Title I selected Format From Other Fields. As you can see in the screen shot below I have selected Album Title, but in the preview window the item being shown that will be changed is the title field and that it will be replaced with the album field. The script is a generic script I copy from a text file to get me started on various routine tasks, ignore the values.
(http://www.xsxpress.net/images/PropertiesBug.jpg)
If you're performing this sort of operation on a large number of files the results could really ruin your day if you don't catch it. I have seen similar behavior on other fields in the last few days.
After posting about this I tried going ahead with the change on one track at a time. The result was the correct field was changed, the bug appears to be in the preview window, not the execution of the script.
As you can see in the screen shot below I have selected Album Title, but in the preview window the item being shown that will be changed is the title field and that it will be replaced with the album field.
The edited field is indicated by the window title. The item column always displays the title and serves as a hint on which line belongs to which track. Not a bug.