I have a different failure mode, in the Home DIY thread I dragged 5 different pictures into the Upload box so they appeared (with the X to remove them in the top right), all good. Hit post. No pictures.
Edit post. Add pictures. Save. No pictures.
Edit post. Add picture. Save. One picture there.
Edit post. Add next picture. Save. Two pictures there now.
Edit post. Add last picture. Save. All pictures there now.