I noticed that the boxcryptor folders can open in mac without the boxcryptor app running. You can try to right click and "Show Package Content" and see the files within the folder. Is the expected behaviour?
of course you can open the folder, but you should be unable to decrypt the files in there. Try to open a file in the Boxcryptor folder and you will not be able to read anything in there :).
Thanks. It classifies my problem.