Environment: MP3tag v3.05 on Windows 10
Today I scanned my MP3 library intending to sort by bitrate, looking for low bitrate files I might need to replace. I noticed that sometimes, the bitrate field would be blank until I selected that row. This is not an issue of a file not having bitrate information, it is a display issue of some kind because the data appears when you click. See the gif below.
Note that doing a select all does not reveal the missing information, nor does a shift-click to select a group.
To try and repro the issue, scan a large set of files and scroll through the list looking for blank bitrates. In my case, bitrate was set to the leftmost column but I don't know if that matters. I did see the problem on 2 different Win 10 systems today. The firs time it had only scanned a couple hundred files, too so I don't think this is an issue specific to a giant library.
Lastly, the tag library was turned on in both test systems. I have not tested to see if that matters.