I'm assuming that you ARE flying up when you do this, and then suddenly the HUD starts working again?
this means you are in a no script area, which ends ~100m above the ground of the parcel with "no-script" set... and if go to a different parcel you shouldn't have any problems.
you can tell this is set from the icon to the right the parcel name at the top of the screen (its a smal scroll icon with a red circle and line symbol at the bottom)... if you mouseover the symbol it will tell you it's meaning