Hello,
I am pretty sure I found a bug in version 10.0.1.0. I connected to a regular (unencrypted) ftp server and a folder named # on the server showed up as a blank name, and I could not navigate into it. Or download it.
Please send a report to GPSoftware support, including the FTP log.
It's possible, depending on the type/version of the server (which the FTP log should indicate), that configuring Opus to use an alternative LIST command for that server will solve the problem.