Required Custom Taxonomy Field - Not Required

Here it is:

<?php
add_filter( 'rwmb_meta_boxes', 'your_prefix_function_name' );

function your_prefix_function_name( $meta_boxes ) {
    $prefix = '';

    $meta_boxes[] = [
        'title'      => __( 'Shifts', 'your-text-domain' ),
        'id'         => 'shifts',
        'taxonomies' => ['shift'],
        'fields'     => [
            [
                'name'        => __( 'Start Time', 'your-text-domain' ),
                'id'          => $prefix . 'shift-start-time',
                'type'        => 'time',
                'placeholder' => __( 'Military Time', 'your-text-domain' ),
                'required'    => true,
                'tooltip'     => [
                    'icon'     => '',
                    'position' => 'top',
                    'content'  => 'Provide the time that the clinical shift starts in military time.',
                ],
            ],
            [
                'name'        => __( 'End Time', 'your-text-domain' ),
                'id'          => $prefix . 'shift-end-time',
                'type'        => 'time',
                'placeholder' => __( 'Military Time', 'your-text-domain' ),
                'required'    => true,
                'tooltip'     => [
                    'icon'     => '',
                    'position' => 'top',
                    'content'  => 'Provide the time that the clinical shift ends in military time.',
                ],
            ],
            [
                'name'     => __( 'Total Hours', 'your-text-domain' ),
                'id'       => $prefix . 'shift_total_hours',
                'type'     => 'number',
                'desc'     => __( 'In hours and minutes are decimals. Visit <a href="https://www.engineeringtoolbox.com/minutes-decimal-hours-d_1699.html">this website for minute decimal values.</a>', 'your-text-domain' ),
                'min'      => 0,
                'max'      => 24,
                'std'      => 12,
                'required' => true,
                'tooltip'  => [
                    'icon'     => '',
                    'position' => 'top',
                    'content'  => 'How many total hours will the student be at the clinical site for this shift? To display hours and minutes use decimals. .',
                ],
            ],
        ],
    ];

    return $meta_boxes;
}