尝试使用imagecreatefromstring保存base64图像，它完全是黑色的

I am trying to take a Base64 encoded image from the database and save it to a file. For whatever reason, when I try using imagecreatefromstring & imagepng the image is completely black. I have tried many different approaches, but I still end up with a black box. Below is my best attempt to get it to work. Any ideas? Thank you so much in advance!I am trying to take a Base64 encoded image from