Hello,
Please try the latest version 2.3.405.746 which has been released today:
https://www.boxcryptor.com/l/download-macosx
If there's still a problem, please send us a debug log so that we can further investigate the issue.
https://support.boxcryptor.com/display/BCOSXEN/How+to+create+a+Debug+log
Best regards,
Robert