Can't view/open images uploaded

All of a sudden, we can’t view any images (jpg, png) that are submitted through our form. They won’t load/download in the browser, although pdfs load fine. For instance, this is an example of an image that won’t load:
https://rugratsva.com/index.php?gf-download=2016%2F07%2FBulldog-pic.jpg&form-id=4&field-id=6&hash=0b7c212aa19d86c76a62e3fe25e4ce3d3b1fb5226e9697c2262dc85e6327f36c

When trying to load in Firefox, it says it cannot be displayed because it contains errors so it sounds like something might be happening during the upload or when trying to view it from the database.

Any ideas what could cause this issue all of a sudden. We want to continue using the plugin!

https://wordpress.org/plugins/si-contact-form/