Mocosloco: This happens on the Creative server. Items: Stained Glass (including the panes) New wood, saplings, and leaves (Dark Oak and Acacia) All new flowers (except the poppy) Blue Orchid, Allium, Azure Bluet, Red, Orange, White, and Pink Tulips, Oxeye Daisy, Sunflower, Lilac, Double Tallgrass, Large Fern, Rose Bush, Peony. I don't exactly have any evidence, but I'm sure it's happened with many others. My game actually crashes when I try to get a hold of some of these items. Anyways, if this is really a glitch/bug or just a plug-in messup, it kinda sucks that you can't use those... If you can, please fix this glitch.
Explanation in detail <--What actually is going on. 1. You cannot connect to another server via a server (For Example from lobby to skyblock), thus j&h uses bungeecord, a proxy. (Read: a proxy, not a plugin, not anything else, what it does is that the proxy fetches whatever you ask it to, for example, when you connect to the proxy, it redirects you to the lobby which is the default server, when you request for skyblock, it redirects you there. CraftBukkit itself does not actually have the ability to redirect players to other server.) BungeeCord is a standalone client. 2. Since BungeeCord is a standalone client/proxy. It is not affiliated with CraftBukkit developers although many large servers like jerry&harry uses it, therefore, it is possible to support vanilla servers as well. Since it is a proxy that does not actually contain the game itself, only connection codes will need to be edited (sometimes) when a new version of minecraft is out, thus a release of bungeecord is much faster than CraftBukkit which needs to recompile tons of changed minecraft code. Therefore, way before CraftBukkit releases a development build, there will be and kinda full build for bungeecord. This means that when 1.7.2 is released, the latest version of bungeecord came out almost instantly while CraftBukkit hasn't even released a development build. 3. Now you maybe screaming at me. What was the point of all that? Well, remember when I said a proxy fetches what you request it to? Well, when you connect to j&h, you are not actually connecting to their lobby but their proxy which redirects you to the default server which is the lobby. Thus, the proxy allows multiple server to be "linked" via portals or /server commands (btw, the /server command is not actually a plugin command but the a proxy command itself). 4. Since a 1.7.2 build for bungeecord is already available and 1.7.2 build for CraftBukkit is not, j&h simply updated the BungeeCord to run the 1.7.2 build thus allowing the proxy to accept 1.7.2 connections (Btw, it supports 1.6.4 connections due to a "protocol error" as one may call it). So since the servers are actually 1.6.4, the items/features are not updated to 1.7.2 so there will be no stained glass code/item id, texture, features in the server. Thus when connecting to the server via Minecraft version 1.6.4 or 1.7.2, you will not be able to use the new items because obviously minecraft version 1.6.4 does not have the 1.7.2 items built into its code and 1.7.2 cannot use the new items as the servers are only really running on 1.6.4 but allowing you to connect to it because the proxy accepts 1.7.2 connections. 5. Now some are also screaming at me. Many of you that are follow @CraftBukkit or @EvilSeph(Leader of bukkit's development team) on twitter or frequently check the craftbukkit website may know that a beta build of it is already out. However, there are many bugs due to the massive tons of code changed in 1.7.2 for example the beta build fixes potion effects on players and mobs not being removed after death. (There are many more bugs.) Also huge plugins like essentials or worldedit, etc have not been updated to 1.7.2 which may cause crashes, loss of data, or simply not working and many other incompatibility issues. Thus I believe that jerry and harry would want the build to become recommended build or for the plugins to update before actually upgrading the server from 1.6.4 to 1.7.2 or higher so as to prevent any mishaps from happening (I know they have upgraded their server previously before the recommended build or the plugins updated but those have lesser amounts of code changes than 1.7.2 I believe, I personally would not take the risk). Hope that answers your questions :D *EDIT*: Copied this from another post that I made, too lazy to replicate the whole thing xD also, please look around the forums for similar threads before creating a new one.
That's a lot to read, and, wow. You sure do know much about Proxy and all of the other stuff you talked about...