Cant see form preview

hello sheritptah!
hello wordpress community!

I’m new to this forum. I’m from Germany and my english is not so good, so if I make some mistakes, please apologize.

I use wordpress 3.7.1 and ninja forms 2.5.3. Which version do you use?
Maybe the same as I do? Because I have quite the same problem as you discribed in your post. But in my case there is no error message or something else. There is only nothing to see. If I edit the page, on the right side there is a possibility to attach a ninja form, but in that drop down menu there is no ninja form to choose. And if I insert the shortcode into my article, there appears a html code if i look on the sourcecode with firebug, but without any displayable content.

Here is a small excerpt of the html code i’ve found:

<div id="ninja_forms_form_1_cont" class="ninja-forms-cont">
		<div id="ninja_forms_form_1_wrap" class="ninja-forms-form-wrap">
	<div id="ninja_forms_form_1_response_msg" style="" class="ninja-forms-response-msg "></div>	<form id="ninja_forms_form_1" enctype="multipart/form-data" method="post" name="" action="" class="ninja-forms-form">

		<input type="hidden" name="_ninja_forms_display_submit" value="1">
	<input type="hidden" name="_form_id"  id="_form_id" value="1">
		<div id="ninja_forms_form_1_all_fields_wrap" class="ninja-forms-all-fields-wrap">
		</div>
		</form>
		</div>
		</div>

I think this issue was created during a wordpress update someday. In my database there are still all form fields defined, but in the wordpress backend nothing is displayed. Only the five forms i’ve created, but without any content. I’ve searched for several hours in the internet (google) and found nothing, but this post here. So I thought I register and write this down here.

I hope someone in this community could help us and give us advice to solve this issue. Thank you in advance.

best regards,
atokirina84