Quote: "I'm not actually relocating an existing HUD, I've made one myself."
But you said...
Quote: "I managed to centre the image by setting the X coordinates to 50 in the global settings"
Why are you messing with the global settings then, because those would be for existing stock HUDs.
A custom HUD should be created and displayed via FPI scripting.
Look in your scriptbank at the pickupkey.fpi for an example of creating and displaying a hud.
Quote: "
;Artificial Intelligence Script
;Header
desc = Pickup Key
;Triggers
:state=0:hudreset,hudx=50,hudy=90,hudimagefine=gamecore\text\pickedupakey.tga,hudname=keyprompt,hudhide=1,hudmake=display,state=10
:state=10,plrdistwithin=40:state=1,playertake,coloff,plrsound=audiobank\misc\ping.wav,hudshow=keyprompt,hudfadeout=keyprompt
:state=1:rundecal=5
;End of Script
"
The parts in bold specify the HUD's locations on the screen.
The Numbers are percentages I think, so the example is in the middle (hudx=50) and near the bottom (hudy=90)
Make sure you are not placing the HUD off screen because of its size.