Dropbox accurately sync all encrypted folders and this can be seen in the screenshot, which I sent in service support.
Screenshot shows that the file in the encrypted form is located in the dropbox folder, but it is not in the Boxcryptor.
I think that if the problem had been in the dropbox, we would not have observed the file in an encrypted form in the dropbox folder at all synchronized devices, but in an encrypted form he is there.
In encrypted form it is available on all devices, and in the not encrypted it is not.
I'm sorry that so many ask questions, but I would like to understand and use the program in full ;)
Thank you for your work!)
P.S. Encrypted files locate at C:\Dropbox\Personal