Just after logging on your local PC, remmina is unable to retrieve password from the gnome keyring.
In some cases, when you logon to your local desktop, the default "Login" keyring is not unlocked by the OS.
Whith the gnome keyring locked, remmina_plugin_glibsecret_get_password() will retrieve a NULL password for the stored remmina profiles, because secret_password_lookup_sync() will never attempt to prompt the user to unlock the keyring.
Is it a secret_password_lookup_sync() bug ?
Gnome keyring unlock fix, fixes #795