MP3Tag not detecting mp3 files on computer

I have just dl MP3Tag to clean up my music files. However, when I select File>Add Directory and navigate to my music library, MP3Tag says "No items match your search." All my music files are mp3's and they are all in one folder. I tried moving a single file to a separate folder and the same thing happens.
Any advice would be much appreciated.
Thanks.

what if you navigate to the file, right click on it, then in the popup menu select 'mp3tag'? does it then open in mp3tag?

Also, have you by chance turned on the "filter" within mp3tag. It's under "view" menu and if on, would show up at the bottom of your screen.

Do not be alarmed.
The standard windows dialogue for selecting folders does not show any files.
So just pick the folder and let mp3tag load the files.
In the status bar at the botton you can see how many files are loaded and how many are displayed.

Well ... Mp3tag provides an error message ...
"_M_ERR_ONLINE_NOTFOUND Sorry, no entries are matching your search criteria."
... but I doubt that this has anything to do wth the circumstances you have described.
Please describe the situation in other words.

DD.20150529.2047.CEST

Just to get this straight:
in the "open folder" dialogue, the search criteria is"where are the folders".
So if you enter a folder that has no more sub-folders, windows is friendly enough to tell you that it has not found any more folders instead of leaving the box completely empty.

There is nothing wrong except the expectation that you should see files.

Thank you all for the replies. Yes, I was expecting to see a list of audio files in the Windows pane. Now that I know that doesn't happen, I will no longer worry. My files are in the process of being re-tagged.