Image resize with intervention and save to s3 not working

I am using Intervention to resize uploaded files and I am having difficulties getting some larger files to save to AWS s3.

Here is my code.

$saved = Image::make($file)->resize($imageSize, null, function ($constraint)
        {
            $constraint->aspectRatio();
            $constraint->upsize();
        })->orientate();

        $newImage = $saved->stream();

        Storage::disk('s3')->put($path .  $name, $newImage->__toString());

This works fine for files up to about 2mb and then I get a server 500 error when trying to upload 5mb jpg's.

This is not an issue with my php.ini as I have it set to 16mb. I am also able to upload 15mb file by using

Storage::disk('s3')->putFileAs($path, $file, $name);

It seems that intervention is causing some kind of issue when I try and get it to save to s3. The thing is I need to resize the images being saved.

I am using dropzone which posts to my route.

Route::post('modal/upload', 'Uploads\UploadController@store')->name('uploads.store');

I have searched endlessly. I have tried using detach() in place of stream() without success.

Any help would be appreciated.

TIA