Open fold when using vim +N file.ext

I'm using an autocmd to unfold lines under the cursor when I open a
file:

autocmd BufReadPost * normal zv

But it doesn't work when opening a file via a line number (vim +N). Is
there a way to get that to work?

My foldopen is:

block,hor,mark,percent,quickfix,search,tag,undo,jump

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