updating named git submodules fails with fatal error - git-submodules

Question

I have worked with git submodules in the past. I know the basic functionality.
If I simply used git submodule add <repo-url> <path/to/submodule>, the .gitmodules file would have :
[submodule "path/to/submodule"]
path = path/to/submodule
url = <repo-url>.git
Recently, I had to add a new git submodule to a repository that I was working on. I also found the fancy --name flag that can be used with the git submodule add command, from the man page of git submodule. The add worked fine and my .gitmodules had :
[submodule "<submodule-name>"]
path = path/to/submodule
url = <repo-url>.git
The issue happens when I'm attempting to update the submodule from the remote :
$ git submodule update --remote
fatal: no submodule mapping found in .gitmodules for path 'path/to/submodule'
OK, I can read the log, so I provide the path/to/submodule next :
$ git submodule update --remote path/to/submodule
Submodule path 'path/to/submodule' not initialized
Maybe you want to use 'update --init'?
OK, if you say so ( though I'm sure that the submodule has been properly initialized before already ). Now :
$ git submodule update --init --remote path/to/submodule
fatal: No url found for submodule path 'path/to/submodule' in .gitmodules
I did some experiments on a test repository and found that this happens only when the submodule is 'named'.
Am I doing something wrong with the name thing of the submodule? According to the man page, the --name flag is only applicable for the add sub-command and it does not work with update.
How do I update such named submodules?