Why is Pdoresource handling the where condition incorrectly?

Question

MODX

Hello!
Straight to the point. Snippet code:

<?php
$where = array(
    'Lo:>=' => 100,
    'Lo:<=' => 140,
);

$where = $modx->toJSON($where);

$output = $modx->runSnippet('pdoResources',array(
    'limit' => 15,
    'parents' => 71,
    'includeTVs' => 'Lo',
    'where' => $where,
    'return' => 'json'
));

return $output;

This snippet produces a result of 4 values, that is, it works correctly. When I change 100 to 99, the result of the snippet is an empty array. Interestingly, when I change 99 to 10, the snippet works correctly.

I don't understand what magic is going on. Help me to understand.