Suddenly missing classes and failing to upload images

I have two potential issues.

The first is that in my existing projects, when I try to load images, I get a message that says "This project doesn't have any classes. Set them up first to be able to annotate." These projects do have classes defined, so I am at a loss for how to fix this.

The second problem is that SA is failing to load images to a new project. The files are 4000 x 6000 pixels (12-13 MB in size). These seem like they should load fine, but they are failing w/o any sort of explanation.

Any help on these issues would be very much appreciated.

Thanks!