Disabling arrow key in insert mode

Hello,

I'm trying to disable the arrow keys in insert mode. I added the following in my vimrc:

inoremap <Left> <Esc>
inoremap <Right> <Esc>
inoremap <Up> <Esc>
inoremap <Down> <Esc>
inoremap <PageUp> <Esc>
inoremap <PageDown> <Esc>

When I'm in insert mode, I now can't navigate left and right.
However, and I press up or down, the cursor still moves and I can still navigate.

Any idea how that could be?

Thank you

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