Featured Image Not Showing (PNG Blank)

The loop on my GD Archive Page is as follows:

[gd_post_title tag='h2']
[gd_post_images type="image"]
[gd_post_images type="image" slideshow="1" show_title="1" animation="slide" controlnav="1"]
[gd_post_address show="icon-label-value" address_template="%%street_br%% "]
[gd_post_meta key="phone"]

On my archive page, some images are not loading. I’ve found a couple commonalities between the images that won’t load:

1. They are PNG images
2. There are no “Place Attachments” or else the place attachments are blank

In addition to solving this PNG issue is there a way for the GD Archive Item loop to pull from the native “Featured Image” field of WordPress rather than “Place Attachments”?

Another irritation of Place Attachments is that they do not allow you to select images from the Media Gallery and instead you must upload these directly from your computer- is this intended?

Thanks in advance for your help!