Upload Sessions attached to Upload Requests can be viewed through the Upload Request link. This will allow you to check data were uploaded to any specific Upload Request link. Open your upload link, and select Uploads:

All data that has already been submitted through the upload link will appear here:

Please confirm all images for the session have been uploaded. It should say (for example) 999 of 999 images uploaded, or the number of images uploaded in your session. If it says (for example) 717 of 999, the upload has stalled and needs to be re-uploaded.