This was added recently. It appears if you upload a mesh with no texture. Roblox makes the assumption that I was trying to upload a texture and a mesh at the same time and then makes a loud noise and steals my input when I don’t. All this does it make it annoying to upload meshes. It should be removed.
A dialog is an action blocker. My actions shouldn’t be blocked if I wasn’t even trying to upload a texture. If you want to give the user some verbose information about the mesh uploading process then you should just put it in the output, where my input isn’t required to proceed.