Can't upload cover images

Hi! I'm having trouble uploading cover images in the Docs section, even after trying with the recommended image size (384 x 192px), JPEG low size images, using the button or dragging the file to the rectangle.

Here's a quick video: https://www.loom.com/share/5b4ae93833004948857e4ad6e780f687?sid=b55b72e0-41a4-4968-9246-60f77828f10d

I don't know if this could be a Bug, but it doesn't seem to work for me.

Thanks in advance.