It sounds like maybe a previous owner has pulled the insulation/dampening material out of its position.

I ran into what sounds like the same problem: heavy, rubber lined fabric stuck in the way without apparent rhyme or reason. I think it's supposed to be glued to the dash above the wires. I ended up working around the fabric to remove the IP. Then when it was out I re-installed the gray fabric back into its correct location. The cut-outs fit around the ducts when I reinstalled it.

If you're really having trouble working upside down in the footwell, I suggest removing the driver's seat. There aren't a lot of fasteners holding it down and it really clears up the working area.

Oh - and safety goggles. Nothing like looking straight up into old dust and disintegrating insulation.