Issues uploading *.jpg media

Hello, I have a multisite configuration- When I attempt to upload media on either my main site or sub sites, I keep getting an error- "Sorry, this file type is not permitted for security reasons."-

We are familiar with the settings at: /wp-admin/network/settings.php- We haven't changed anything. we currently have these settings saved- jpg, jpeg, png, gif, mp3, mov, avi, wmv, midi, mid, pdf, xls, wav, mp4, docx, pptx but cannot add a simple jpg file to the media library.

Anyone else having this issue?