I am having the same issue right now. It has happened to me many times and every time it's when I get a bunch of group texts at the same time, they all just say "downloading" and take forever (hours sometimes) to go through. Typically they finally break through together all at the same time and I get them all at once. This happens whether I'm connected to wifi or not. This has happened to me on the galaxy s6 previously, and now on the note 9. This is a long standing issue...will you PLEASE fix it? We are getting locked out of conversations and it is very frustrating.