You could try mounting the connected drive on your Mac/Windows desktop. Then, within the mounted drive, navigate to /storage/nas (the mount point for your SMB server drive).
But don’t you get some feedback within the sonicTransporter Settings/Drive Mounter window on your browser? I don’t remember if I did or not. My Drive Mounter settings look like this:
By the way, I had problems like yours, but then yesterday the share drive mysteriously became accessible again (without going through the procedure I described in the link above.)