No databases are displaying when trying to import MIDB's in section 4, option 1 of the MCC.
Remove all icons (if they are stacked) for the NAB from the Lotus Notes Workspace. Click on it and use the delete key. Once they are ALL removed, close the Lotus Notes Client and reopen it. Add the NAB back to the Workspace.
If this does not work, this could be a cached design element in Notes on the Migration Controll Center (MCC)
1. Remove all the icon from the domino NAB of of the Workspace and remove the Notes Migrator database icon from the Workspace.
2. Open the cache.ndk local (File -> Database -> Open, and in the File name box, type "cache.ndk").
3. Go the (byurl) view, select all the documents and delete them.
4. Open the bookmark.nsf local:
a. In the Workspace, highlight the bookmark icon.
b. Hold down the SHIFT and CTRL keys, and from the menu, select View -> Go to -> hidden view (byurl).
c. In the same view, select all document and delete them.
5. Close the Notes client and then reload it.
Run the steps to import.
If this does not resolve the issue, please review the following article: NM: Empty dialog when importing Mail In Databases