Upgrading from Minecraft 1.12 to 1.13+

If you're upgrading from Minecraft 1.12 (or previous versions) to 1.13+, icons inside holograms may not work (they will display as bedrock) because the internal names have changed. The solution is to manually update them.

List of valid Material names for 1.13+ (you can't use the ones with the LEGACY prefix)