Square boxes are displayed instead of regular double-byte characters if you name catalogs, people, places, events, tags, and so on, using double-byte characters. 

This problem occurs only on a Windows 10 non-Japanese OS (for example English or German). The problem does not occur with the Japanese OS. 

Workaround

Use a Japanese version of Windows 10. Alternatively, install a Japanese font on the computer running the Windows 10 non-Japanese OS.