Python FTP.mlsd doesn't work when passed current directory "." (ftplib.error_perm: 550 Unable to handle command)

Question

When using mlsd I get an error when I pass '.' as the path.

import ftplib
ftp = ftplib.FTP_TLS('hostname.com', user='myusername', passwd='mypassword')
list(ftp.mlsd()) # Returns directory listing as expected
list(ftp.mlsd('.')) # Yields an error

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.10/ftplib.py", line 590, in mlsd
    self.retrlines(cmd, lines.append)
  File "/usr/lib/python3.10/ftplib.py", line 462, in retrlines
    with self.transfercmd(cmd) as conn, \
  File "/usr/lib/python3.10/ftplib.py", line 393, in transfercmd
    return self.ntransfercmd(cmd, rest)[0]
  File "/usr/lib/python3.10/ftplib.py", line 793, in ntransfercmd
    conn, size = super().ntransfercmd(cmd, rest)
  File "/usr/lib/python3.10/ftplib.py", line 359, in ntransfercmd
    resp = self.sendcmd(cmd)
  File "/usr/lib/python3.10/ftplib.py", line 281, in sendcmd
    return self.getresp()
  File "/usr/lib/python3.10/ftplib.py", line 254, in getresp
    raise error_perm(resp)
ftplib.error_perm: 550 Unable to handle command

Note: The error only appears once you start to iterate over the generator, so the list() is required. (next() works too)

I thought it might be interpretting the . as a file/directory name, but if that were the case I'd expect it to say No such file or directory instead of Unable to handle command.

It appears that other people have used "." as an argument to mlsd so I'm not sure what I'm doing wrong.