You can try this:
1. Close the Library Manager, or anything that has the Library open.
2. Make a backup copy of your Library directory.
3. In your library directory, delete the SysIndex.cbf file
4. Open the Library Manager double clicking on the library .LMC file in your library directory.
5. This should rebuild the indexing while the library opens. Note any errors and check logs.
6. Try the Import/Export again to see if all is OK.