How to make locked files under SVN source control visible to others?

We use MATLAB build-in SVN functionality to develop some algorithm involving several m-functions in a team. Repository is stored on dedicated SVN-Server. In order to avoid double work, we like to use the lock-file feature. To do so, we have modified config-file, stored at C:\Users\<user>\AppData\Roaming\Subversion :

### Section for configuring miscellaneous Subversion Options ([miscellany]).

enable-auto-props = yes

and

### Section for configuring automatic properties ([auto-props])

*.m = svn:needs-lock=yes

So far, this is what we understood is to do. Unfortunately, - no warning is issued if someone modifies an m-file without having it locked before - if a file is locked by user A this does not become visible to other users of developer team (by padlock Symbol)

The only effect we see is that when a file has been locked by user A and user B modifies it simultaneously, user B gets notification about status of file (locked) when user B wants to "View and Commit Changes". This is not satisfactory as we exactly want to avoid this.

What has to be done that locked files get visible to other users and to make this "lock-file-before-modify" feature really working? Thanks for your support.