Drupal-Modals have 0 height

Ok. Just to be sure, you see it working in the Claro theme?

We set the modal in code like this:

$form['edit_task_complete'] = [
    // In the UI to be editing.
      '#type' => 'link',
      '#title' => 'Edit Task',
      '#prefix' => '<div class="maestro_hidden_element">',
      '#suffix' => '</div>',
      '#url' => Url::fromRoute('maestro_template_builder.edit_task', ['templateMachineName' => $templateMachineName]),
      '#attributes' => [
        'class' => ['use-ajax'],
        'data-dialog-type' => 'modal',
        'data-dialog-options' => Json::encode([
          'width' => '90%',
          'height' => '100%',
          'dialogClass' => 'modal-task-edit',
          'position' => [
            'my' => 'center',
            'at' => 'center',
          ],
        ]),
      ],
    ];

Where we set the width and height, which is indeed reflected in the outer modal DIV:

<div style="position: fixed; height: auto; width: 90%; top: 26.46px; left: 107.2px;" tabindex="-1" role="dialog" aria-modal="true" class="ui-dialog modal-task-edit ui-widget ui-widget-content ui-front ui-dialog-buttons" aria-labelledby="ui-id-12">

Same DIV output you've shown exists and works in Claro.

Let me know if you've come up with a GIN-specific fix. If not, I'll have to dig into this a bit further.

@chriszz
I've pushed a fix for this. You can try the DEV release or wait until I roll a new version (coming soon).

Works for Claro and Gin (and should work for other themes as well)