To reproduce the bug, do the following step:
- Select a file in the file list.
- Click on a a field of the file to edit that field.
- Hold the SHIFT key.
- Click on another file in the file list to select all the files between them.
The fields in the Tag Panel become the value of the first file. If you click "Save" at this time, all the tags in all the files you selected will become the same with the first file.
The fields in the Tag Panel should become "< Keep >" if the field value of the selected files is not all the same.