Incomprehensible condition and incorrect operation of the function

There is the following code (demo here), the function (with recursion) go the matrix in a spiral collecting values:

function spiralmatrix($arr)
{
    return  $arr 
            ? array_merge(
                    array_shift($arr), 
                    spiralmatrix(array_reverse(transpose($arr)))
            )
            : $arr;
}

function transpose($arr)
{ 
    return $arr
            ? count($arr) == 1
                ? array_chunk($arr[0], 1) 
                : array_map(null, ...$arr)
            : $arr;
}

I understand that using multiple ternary expressions contributes to unreadable code. But there is more predominant sporting interest for code-Golf.

And so, to the question, is it possible to somehow change the condition to cut more characters? Can use any methods.

I would also like to ask, it is strange that the following works fine (demo):

function transpose($arr)
{ 
    return $arr
            ? count($arr) == 1
                ? array_chunk($arr[0], 1) 
                : array_map(null, ...$arr)
            : $arr;
}

And the expression works a little wrong (demo):

function transpose($arr)
{ 
    return count($arr) > 1 ? array_map(null, ...$arr) : $arr; 
}

Although, in separate tests (not in this function spiralmatrix) they show the same results what can is this problem? (demo comparisons). Grateful for any help..

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