There are errors in logs now.

Undefined offset: 0 {"userId": xxxxx,"exception":"[object] (ErrorException(code: 0): Undefined offset: 0 at /wp-content/plugins/intuitive-custom-post-order/intuitive-custom-post-order.php:291)

Temporary workaround, changed rows 269 and 291 with

if ( !isset($result[0]) || $result[0]->cnt == 0 || $result[0]->cnt == $result[0]->max ) continue;

i.e. added this, hope it helps

!isset($result[0]) ||