displayUsing() doesn't display anything

[frederiksimon]

When using displayUsing function on multiselect field, it doesn't display the returned value in resource listing.
Editing form has correct values for the pivot field, only issue is with the displayed values.

My code:

            `MorphToMany::make(__('genericProperties'), 'genericProperties', config('eshop.eshop_generic_property_resource'))
                ->fields(function($request, $field) {
                    return [
                        \Outl1ne\MultiselectField\Multiselect::make(__('genericPropertyValues'), 'with_generic_property_values')
                            ->dependsOn(['genericProperties'], function (\Outl1ne\MultiselectField\Multiselect $field, NovaRequest $request, FormData $formData) {
                                $genericPropertyId = (int) $formData->resource(GenericProperty::uriKey());

                                $options = \Models\GenericPropertyValue::query()
                                    ->where('generic_property_id', '=', $genericPropertyId)
                                    ->get()->mapWithKeys(function ($item) {
                                        return [$item->id => $item->value];
                                    })
                                    ->toArray();

                                $field->options($options);
                            })
                            ->displayUsing(function () use ($field) {

                                $genericPropertyValuesIds = json_decode($field->pivot->with_generic_property_values);

                                $genericPropertyValues = config('eshop.eshop_generic_property_value_model')::query()
                                    ->whereIn('id', $genericPropertyValuesIds)
                                    ->get();

                                $displayText = '';

                                foreach ($genericPropertyValues as $value) {
                                    $displayText = $displayText . $value->value . ' | ';
                                }

                                return rtrim($displayText, ' | ');
                            })
                    ];
                }),`

[Tarpsvo]

Heya! I'd be really grateful if you'd help with debugging this and submit a PR if you find out what's causing displayUsing to not work. I currently don't have the time to look into this. :( Sorry.