Thanks for taking the time to open a bug report!

Describe the bug
Sometimes the item names and lore are displayed sometimes not. I have not discovered a consistent pattern, but it is new with Spigot 1.16.

To Reproduce
Steps to reproduce the behavior:

1. Define multiple IJ items in hotbar (slot 8) and not (slot 17) that activate based on permissions and worlds.
2. Open the inventory.
3. Observer that name/lore are not always displayed

Expected behavior
Consistent display of name and lore.

For example, this IJ item is configured for all worlds

  changeWorld-tool:
    id: CLOCK
    slot: 8
    count: 1
    name: '&bNavigate'
    lore:
      - 'Teleport elsewhere'
    commands:
      right-click:
        - 'deluxemenus open navigation4'
    itemflags: cancel-events, death-drops, hide-attributes, hide-durability, inventory-modify, placement, self-drops, unbreakable
    triggers: join, respawn, world-change
    permission-node: 'deluxemenus.open'
    # disabled-worlds-UNSUPPORTED: world_void
    enabled-worlds: world, world_lobby, world_blackdog, world_city, world_luckyblock, world_minigames, world_skyblock, world_westeros, world_whitedog, world_yellowdog

.
Screenshots
In one world, correct

In another world, incorrect

The navigation menu is popped in both cases, so the item definition basically works. Only the name and lore are problematic.

.
Please complete the following information:

>version
[11:56:22] [Server thread/INFO]: This server is running CraftBukkit version git-Spigot-beb7d47-145921e (MC: 1.16.1) (Implementing API version 1.16.1-R0.1-SNAPSHOT)
[11:56:22] [Server thread/INFO]: You are running the latest version
>version ItemJoin
[11:56:37] [Server thread/INFO]: ItemJoin version 5.0.7-SNAPSHOT-b448
[11:56:37] [Server thread/INFO]: Get custom items on join.
[11:56:37] [Server thread/INFO]: Website: https://www.spigotmc.org/resources/itemjoin.12661/
[11:56:37] [Server thread/INFO]: Author: RockinChaos

So I am going to be pretty blatant. After 5 days of fully testing this, I could not replicate it.

Things to note;
1.) I see several open issues on the hub.spigot repository claiming issues with name/lores being sterilized which is exactly what this looks like.

My suggestions;
1.) Install the latest snapshot of ItemJoin as it has a lot of 1.16 fixes; http://ci.craftationgaming.com/job/ItemJoin/472/
2.) Compile a new version of 1.16.1 using --rev for the BuildTools.jar so you get the absolute newest spigot version compiled.

Let me know if this still continues, if it does can you check if the items still function after being sterilized?

As you may recall, I run a pair of test servers, and keeping them up-to-date with Spigot and the dev versos of 150+ plugins is a full-time occupation when there are major changes as were presented for the transition from 1.15.2 to 1.16.1. After six days things change a lot in SpigotLand: on average, 4 changes/day for ItemJoin and more for Spigot; other plugins we test have produced similar challanges. As of this morning, I could still replicate the issue with

>version
[02:08:09] [Server thread/INFO]: This server is running CraftBukkit version git-Spigot-c3a49df-72f3689 (MC: 1.16.1) (Implementing API version 1.16.1-R0.1-SNAPSHOT)
[02:08:09] [Server thread/INFO]: You are running the latest version
>version ItemJoin
[02:08:13] [Server thread/INFO]: ItemJoin version 5.0.7-SNAPSHOT-b472
[02:08:13] [Server thread/INFO]: Get custom items on join.
[02:08:13] [Server thread/INFO]: Website: https://www.spigotmc.org/resources/itemjoin.12661/
[02:08:13] [Server thread/INFO]: Author: RockinChaos

However, I just remembered the resolution of a previous issue. I executed

• /ij removeAll
• /ij getAll

in each of 23 worlds, and now all is well. Correct name and lore are displayed for each item in each world.