I was having trouble to. I put my image into dropbox, then right clicked and “copied image address”, then I pasted it into the pop up when I used img. BUT, be sure to delete the extra http://, otherwise it won’t work. Hope this helps!
Well I don’t feel like fighting with this right now, so here are links to my first two sketches. First one is a sketch of my friend, the second is a quick landscape sketch, with reference from the game Bastion.