Nova Action does not pass content from textarea input field to backend for processing

This is a follow-up from https://laracasts.com/discuss/channels/nova/creating-items-and-related-records-in-bulk-using-nova...

I have a Nova action to import URLs in bulk and attach to a model. I created the source and registered it to the resource like this:

    public function actions(NovaRequest $request): array
    {
        return [
            (new ImportSources())->showInline()
        ];
    }

Here is my handle method for the action:

    public function handle(ActionFields $fields, Collection $models): mixed
    {
        DB::beginTransaction();

        try {
            // Split the string by new lines and filter out any empty values
            $rawData = $fields->get('URLs');
            Log::info('Raw input data:', ['data' => $rawData]);

            $lines = array_filter(preg_split('/\r\n|\r|\n/', $rawData));
            Log::info('Processing lines:', ['lines' => $lines]);

            foreach ($lines as $line) {
                // Extract URL using regular expression
                // This pattern matches URLs in Markdown links or standalone URLs
                if (preg_match('/\bhttps?:\/\/\S+|\((https?:\/\/\S+)\)/i', $line, $matches)) {
                    $url = trim($matches[0], '()'); // Remove parentheses if they exist

                    // Log extracted URL
                    Log::info('Extracted URL:', ['url' => $url]);

                    // Normalize the URL
                    $normalizedUrl = rtrim($url, '/');
                    $normalizedUrl = preg_replace('/#:~:text=.*$/', '', $normalizedUrl);

                    // Log normalized URL
                    Log::info('Normalized URL:', ['url' => $normalizedUrl]);

                    // Check if the URL exists in the sources table
                    $source = Source::firstOrCreate(['url' => $normalizedUrl]);

                    // Log source creation or retrieval
                    Log::info('Source retrieved or created:', ['source' => $source]);

                    foreach ($models as $model) {
                        // Attach the source to the Thread
                        $model->sources()->syncWithoutDetaching([$source->id]);

                        // Debugging: Check attached sources
                        $attachedSources = $model->sources()->get();
                        Log::info('Attached sources:', $attachedSources->toArray());
                    }
                } else {
                    // Log if no URL is matched
                    Log::warning('No URL matched in line:', ['line' => $line]);
                }
            }

            DB::commit();
            return Action::message('URLs have been processed and attached successfully!');
        } catch (\Exception $e) {
            DB::rollBack();
            // Log the exception
            Log::error('Error during URL processing:', ['error' => $e->getMessage()]);
            return Action::danger('An error occurred: ' . $e->getMessage());
        }
    }

Here is my field definition:

    public function fields(NovaRequest $request): array
    {
        return [
            Textarea::make('URLs')
                ->rules('required')
                ->help('Paste the sources here, one URL per line.'),
        ];
    }

When I log the above code I only see the below which seems to indicate the URLs I am importing are not getting passed from the textarea field to the backend for processing:

[2023-12-26 18:21:27] local.INFO: Raw input data: {"data":null} 
[2023-12-26 18:21:27] local.INFO: Processing lines: {"lines":[]} 

When I inspect Network in the browser I do not see any requests being made. I don't see any JavaScript errors. I can confirm the rest of my code is working as expected because if I hard code $rawData with URLs the URLs are attached to my model.