It seems that I can only use the !LINK tag on just two LCD panels.
I used it on a pair of panels and it worked just fine, I then tried to use it on a second pair of panels, and those panels go blank.

Working panels:
LCD Ops Inventory Panel 1 [LCD] !LINK:LCD Ops Inventory Panel 1 1
LCD Ops Inventory Panel 1A [LCD] !LINK:LCD Ops Inventory Panel 1 2

Panel 1 Custom Data:
Center << Total Cargo >>
CargoX {Cargo}
Center ----------------------------------------------------------------------------------------
echo
Center << Main Cargo Container A >>
CargoX {Main Cargo A}
echo
Center << Main Cargo Container B >>
CargoX {Main Cargo B}
echo
Center << Ice Cargo Container A >>
CargoX {Ice Cargo A}
echo
Center << Ice Cargo Container B >>
CargoX {Ice Cargo B}
echo
echo
Center << Components Cargo Container A >>
CargoX {Components Cargo A}
echo
Center << Components Cargo Container B >>
CargoX {Components Cargo B}
echo
Center << Ore/Ingots Cargo Container A >>
CargoX {Ore/Ingots Cargo A}
echo
Center << Ore/Ingots Cargo Container B >>
CargoX {Ore/Ingots Cargo B}

These panels work flawlessly.

Blank Panels:
LCD Ops Inventory Panel 3 [LCD] !LINK:LCD Ops Inventory Panel 3 1
LCD Ops Inventory Panel 3A [LCD] !LINK:LCD Ops Inventory Panel 3 2

Panel 3 Custom Data:
Center << Base Inventory List >>
Center -----------------------------------------------------------------------------------------
echo
InventoryX

These panels are completely blank.

I've spent several hours experimenting and it seems like no kind of custom data works on the second set of panels (3 and 3A), unless I remove the !LINK: tag, then anything that I put on each individual panel works perfectly.

I'm at my wits end. I loved this script, until I hit this brick wall, now I'm coming to hate it, and that's simply not acceptable. This script does everything else incredibly well.