Since the RPG-HUD mod doesn't render the HUD in creative mode, the feature also blocks rendering with the Better HUD's HUD screen. I tried in minecraft 1.12.1 with both two mods and only Better HUD mod.
Here's the Better HUD
http://www.minecraftforum.net/forums/mapping-and-modding/minecraft-mods/2314863-better-hud-1-3-9-adds-28-new-customisable-elements

You are using both RPG-HUD and Better HUD? And neither shows up?

I tried with only those 2 mods and both two mod's HUD don't be seen in creative mode.
Maybe RPG-HUD forces not to be seen its HUD and other mods HUD.

I think this may be fixed if you add toggle feature to render the HUD in creative mode.

this is fixed with 3.7. RPG-Hud no longer overwrites events. If better HUD uses the appropiate events for rendering, it will work.