Spigot 1.13.2 latest
ItemJoin 4.9.1-b155

Custom lore is not displayed with the item in slot 17. Custom lore is displayed if I change the slot to the hotbar (say, slot 7).

  identifier-lobby:
    id: BRICKS
    slot: 17
    count: 1
    name: '&bLobby'
    lore:
      - 'world identifier'
      - 'op only'
    permission-node: 'blackdog.op'
    itemflags: cancel-events, death-drops, hide-attributes, hide-durability, inventory-modify, placement, self-drops, unbreakable
    triggers: join, respawn, world-change
    enabled-worlds: world_lobby

No errors on /itemjoin reload.

I apologize for the late reply, bouncing back and forth between the new and older framework of ItemJoin is a bit jarring.

I have tested this but I am unable to replicate this issue.
Are there any other plugins you are using in the same instance as ItemJoin? I know some plugins have an inventory "sterilizer" that removes any modifications to certain items.

4.9.1-b155 (tested and shows the custom lore).
I have attached a screenshot, please let me know if I am missing something.

Well, sure. Current n(plugins)=86. But none of them advertise inventory sterilization. Which plugins were you thinking of? I'll send a list in PM.

Interestingly, lore for the CLOCK in slot 8, which is also an ItemJoin item, is visible.

Yeah, theres no reason the item should be hiding the lore, especially promatically. I have been going through each plugin you sent me but 86 plugins takes a while...

More experimentation. I changed the BRICKS (above) to CLOCK. Reloaded ItemJoin, and changed world and /back to reload the IJ items. The lore is visible. So type of item is important. I suspect it has to do with whether lore can be assigned "naturally" to the item.

More experimentation. I changed the CLOCK back to BRICKS. Reloaded ItemJoin, and changed world and /back to reload the IJ items. The lore is visible. WTF?

I disconnected/reconnected. The lore is visible.

Like I said its sounding more and more like a plugin sterilized the item randomly. Also if you were messing with animation itemflag on the bricks item before the b145 I think, there was a bug fix for the lore not being displayed properly on animated items so it would set a blank lore.

I don't use the animate itemflag. The lore specification exists in the items.yml file (per above). It just isn't (wasn't) displayed.

Should I just reset all the items that are currently missing lore, and call it "fixed"?

I would say that is the best idea but if it reappears as an issue it is definitely another plugin. I will continue to go down the whole list of plugins you sent me though and see if I find anything.

Thanks.

The newly-displayed lore is retained across server restarts. That's good. :)

You know, I test a lot of plugins. It could be one that I tested and discarded as not very good.

Hmmm possibly true. I am 31 plugins down so far lol.

Since the lore is defined by ItemJoin, is it possible to enforce it when the objects are loaded? I imagine that I could construct a test case, by removing the lore, then replacing the definitions before a reload.

This issue (if it is specific to ItemJoin would have been most likely) officially fixed in the release of ItemJoin v5.0.0.
You can grab it here; https://www.spigotmc.org/resources/itemjoin.12661/download?version=254090

Please read the changelog as the documentation has not been updated yet;
https://www.spigotmc.org/wiki/recent-changes

(I apologize for the late response, I was unable to completely go through the plugin list you sent me due to lack of time while preparing for this update). Please re-open this issue if the same issue occurs.