Password is sometimes '.'

[h6w]

On Ubuntu 18.10, the Remmina account lists the password as:

password=. 

I understand this means that the actual password is stored in the Gnome Keys and Passwords Tool (a.k.a. "seahorse") by clicking View -> Any.

[peppelinux]

I coded some years ago this.
This way you should get the passwords, let me know