Can't submit form with "attributes" input field - html

Question

I have a form with the following setup:
<div class="row">
<div class="col-3">
#include('acp.sidebar')
</div>
<div class="col-9">
#if (count($errors) > 0)
<div class="alert alert-danger">
<ul>
#foreach ($errors->all() as $error)
<li>{{ $error }}</li>
#endforeach
</ul>
</div>
#endif
<form class="form-horizontal" role="form" method="POST" action="{{ url('acp/provider/add') }}" enctype="multipart/form-data">
{{ csrf_field() }}
<input type="hidden" name="id">
<fieldset>
<legend>Grunddaten</legend>
<div class="form-group">
<label for="name">Name</label>
<input type="text" class="form-control" id="name" name="name" required>
</div>
<div class="form-group">
<label for="description">Beschreibung</label>
<textarea class="form-control" id="description" name="description" required></textarea>
</div>
<div class="form-group">
<label for="url">Domain</label>
<input type="text" class="form-control" id="url" name="url" required>
</div>
<div class="form-group">
<label for="ref">Ref-Code</label>
<input type="text" class="form-control" id="ref" name="ref" required>
</div>
<div class="form-group">
<label for="image">Logo</label>
<input type="file" name="image" id="image" class="form-control" accept="image/*">
</div>
<div class="form-group">
<label for="checkboxes">Payment-Anbieter</label>
<div>
#foreach($paymentProviders as $key => $provider)
<label class="checkbox-inline" for="checkboxes-{{$key}}">
<input name="paymentProviders[]" id="checkboxes-{{$key}}" value="{{$provider->id}}" type="checkbox">
<img src="{{url('/images/paymentProvider/small/'.$provider->image)}}">
{{$provider->name}}
</label>
#endforeach
</div>
</div>
</fieldset>
<fieldset>
<legend>Crawler</legend>
<div class="form-group">
<label for="attributes">Suchattribute</label>
<input type="text" class="form-control" id="attributes" name="attributes" required>
</div>
<div class="form-group">
<label for="crawlerType">Typ</label>
<select id="crawlerType" name="crawlerType" class="form-control">
#foreach($crawlerTypes as $crawlerType)
<option value="{{$crawlerType}}">{{$crawlerType}}</option>
#endforeach
</select>
</div>
</fieldset>
<div class="form-group">
<div class="pull-right">
<button type="submit" class="btn btn-primary">
Absenden
</button>
</div>
</div>
</form>
</div>
</div>
As you can see there is a input named "attributes" down below. When I add this, I can't submit my form. It's like clicking on a button with no "submit" attribute.
After removing or renaming this input, it works. It's not a big thing to rename my input - I'm just interested if this is a bug, or a for me unkown feature.
I'm using Bootstrap v4.0.0-alpha.6 and Laravel 5.4.22.