Running LuckPerms v5.0.83 by Luck.
-  Platform: Sponge
-  Server Brand: SpongeForge
-  Server Version:
-  SpongeAPI: 7.1.0-ea50f0c2 - SpongeForge: 1.12.2-2838-7.1.9
-  Storage:
-     Type: MariaDB
-     Ping: 0ms
-     Connected: true
-  Messaging: Sql
-  Instance:
-     Static contexts: server=dev
-     Online Players: 1 (1 unique)
-     Uptime: 1m 6s
-     Local Data: 1 users, 9 groups, 0 tracks

SpongeForge
    Minecraft: 1.12.2
    SpongeAPI: 7.1.0-ea50f0c2
    Sponge: 1.12.2-7.1.9
    SpongeForge: 1.12.2-2838-7.1.9
    Minecraft Forge: 14.23.5.2838
    JVM: 1.8.0_232/64-bit (Oracle Corporation)
    OS: Linux (4.9.0-11-amd64/amd64)

Setting a permission to a group or user specifying a context and then checking if that user (or a user in that group) has the permission will say the value is undefined.

How to reproduce the issue:

• Check the available contexts for yourself /lp user KaiNoMood info. My IGN is KaiNoMood, change it with your own IGN. Any context will do.
  
• Set yourself a test permission with a context: /lp user KaiNoMood perm set test.permission world=world.
  
• Use /lp user KaiNoMood perm checkinherits test.permission. It will say you do not inherit the permission.
  
• At the same time, if you give yourself /lp user KaiNoMood perm set test.nocontext and check it with /lp user KaiNoMood perm checkinherits test.nocontext, it'll say you inherit the permission.
  

This makes plugins saying the players do not have the permission if contexts are used. Using the "extension-legacy-api" does not change the behaviour. Tested in a Pixelmon server without any other plugin or mod.

Example code:

public void test(Player player) {
  if (player.hasPermission("test.permission")) {
    player.sendMessage(Text.of("You have test.permission"));
  } else {
    player.sendMessage(Text.of("You do not have test.permission"));
  }
}

This shows "You do not have test.permission" when contexts are used, even if the player got the context.

Contexts work fine under LuckPerms-Bukkit-4.4.27 on a Spigot 1.8.9 server (I have been using Contexts for years and they have been working just fine).
I'd like to downgrade to 4.4.x for SpongeForge so I can use contexts, but I can't find the jar.

Thank you very much for reading, have a nice day/night!

Does it work if using /lp user KaiNoMood permission checkinherits test.permission world=world?

Yes, that command does work. Still, the "hasPermission" method issue persists.

I tested with similar setup on my network and can confirm it’s not working.

Can you try to debug with verbose?

Sorry I actually performed several tests and the issue seems a different one and it involves custom ContextCalculators. I think it is less messy if I just close this issue and open a new one after I gathered all the details.