title: Replace "n\a" values with missing values in R / tidyverse
body: <p>I am looking for an explanation of why this tidy way to replace <code>&quot;n\a&quot;</code> with <code>NA</code> doesn't work:</p>
  <pre><code>dta &lt;- tibble(var1 = c(&quot;1&quot;, &quot;2&quot;, &quot;n/a&quot;), var2 = c(&quot;n/a&quot;, &quot;2&quot;, &quot;4&quot;))
  
  &gt; dta %&gt;% mutate(across(everything(), na_if, &quot;n/a&quot;))
  # A tibble: 3 x 2
    var1  var2 
    &lt;chr&gt; &lt;chr&gt;
  1 1     n/a  
  2 2     2    
  3 n/a   4 
  </code></pre>