vimdiff - how to jump to next difference in long line - shortcut ]c does not work

Hi,
I have files with long lines and when doing diff it is time consuming to move to the diff change (marked red in vimdiff).

I have searched the help:
:h jumpto-diffs

With explanation that:
]c
should jump to the next start of the change.

But in my case this key shortcut does nothing.

I started gVim on Windows 7 with command:
gvim -u NONE -N
and key shortcut still does not work.

Maybe this is related to my keyboard (Slovenian keyboard):
See keyboard layout: https://gate2home.com/Slovenian-Keyboard
I have to press <Right-Alt> to get ] key.

Any idea what is wrong? Any workaroud?
I tried to use mapping like:
:map a ]c
and when pressing a nothing happens.

My gVim is v8.0.1529 witch is latest nightly build for win32 from:
https://github.com/vim/vim-win32-installer/releases/download/v8.0.1529/gvim_8.0.1529_x64.zip

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