Proxy error: SOCKS proxy did not accept our authentication

Script: Retrospectively logging previous script records:
Script: open sftp://xxx@xxx -hostkey="ssh-rsa 2048 xxxxxxxxx" -rawsettings ProxyMethod="2" ProxyHost="xxxx.xxxx.com" ProxyPort="1080"
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Session name: xxx@xxx (Ad-Hoc site)
Host name: xx.xx.xx.xx (Port: 22)
User name: XXX (Password: Yes, Key file: No, Passphrase: No)
Tunnel: No
Transfer Protocol: SFTP
Ping type: Off, Ping interval: 30 sec; Timeout: 15 sec
Disable Nagle: No
Proxy: SOCKS5
HostName: xxxx.xxxx.com (Port: 1080); Username: ; Passwd: No
Send buffer: 262144
SSH protocol version: 2; Compression: No
Bypass authentication: No
Try agent: Yes; Agent forwarding: No; TIS/CryptoCard: No; KI: Yes; GSSAPI: No
Ciphers: aes,chacha20,blowfish,3des,WARN,arcfour,des; Ssh2DES: No
KEX: ecdh,dh-gex-sha1,dh-group14-sha1,rsa,WARN,dh-group1-sha1
SSH Bugs: Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto,Auto
Simple channel: Yes
Return code variable: Autodetect; Lookup user groups: Auto
Shell: default
EOL: LF, UTF: Auto
Clear aliases: Yes, Unset nat.vars: Yes, Resolve symlinks: Yes; Follow directory symlinks: No
LS: ls -la, Ign LS warn: Yes, Scp1 Comp: No
SFTP Bugs: Auto,Auto
SFTP Server: default
Local directory: default, Remote directory: home, Update: Yes, Cache: Yes
Cache directory changes: Yes, Permanent: Yes
Recycle bin: Delete to: No, Overwritten to: No, Bin path: 
DST mode: Unix
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Leaving host lookup to proxy of "xx.xx.xx.xx" (for SSH connection)
Will use SOCKS 5 proxy at xxxx.xxxx.com:1080 to connect to xx.xx.xx.xx:22
Looking up host "xxxx.xxxx.com" for proxy
Connecting to SOCKS 5 proxy at xx.xx.xx.xx port 1080
Connecting to xx.xx.xx.xx port 1080
We claim version: SSH-2.0-WinSCP_release_5.9.4
Proxy error: SOCKS proxy did not accept our authentication