problems with "pass" shortcode

Hi!

When I pass a field value into the loop, it works only if a value is a single word, e.g.

[pass field=prize]
[loop type=books field=prize_1 value={FIELD}]
<tr>
    <td>[field author]</td>
    <td>[field title]</td>
    <td>[field year]</td>
  </tr>
[/loop]
[/pass]

works only if prize=man_booker_prize,
but not if prize=man booker prize.

What am I doing wrong?

https://wordpress.org/plugins/custom-content-shortcode/