I wanted to upload my pic here, but it always says "The uploaded file is empty". I thought it may be too large, so I shrunk it to be lower than 200mb and it's still showing the same error.
Hmmm I just tested and could upload a .png screenshot of my desktop just fine. No issues when either attaching it or when submitting the post.
Is there any error message when trying to add an attachment or when submitting the post with the attachment ? There's also nothing in general about attachments in forum administration logs, so if there's some PHP issue then probably sysadmins would need to take a look at the server level.