I have recently run into a related issue. My hud for a certain pair of shoes was off screen. Putting it into edit from my inventory I could easily adjust the up/down (Blue) or side to side (Green) axis. However when I took the hud out of edit it disappeared as if the hud had moved behind my camera's view. I'm sure this is a computer resolution problem but I didn't know how to fix it. However, I finally realized if I put the hud in edit and selected my objects tab I could see the third (Red)axis and by increasing it's positive value I could bring it into view.