How is the log in Console:
[14:24:04 INFO]: [LP] warrior had prefix '(Warrior)' set at a priority of 100 in context server=.

lp group warrior meta info
[14:24:07 INFO]: [LP] warrior's Prefixes
[14:24:07 INFO]: [LP] -> 100 - '(Warrior)' (inherited from self) (server=)
[14:24:07 INFO]: [LP] warrior has no suffixes.
[14:24:07 INFO]: [LP] warrior has no meta.
[14:24:17 INFO]: RareDragon: e
[14:26:24 INFO]: RareDragon: Test

When setting the server up:
[14:10:45] [Server thread/INFO]: [LuckPerms] Enabling LuckPerms v4.0.80
[14:10:45] [Server thread/INFO]: �[0;36;1m __ �[0;36;22m __ ___ __ __ �[m
[14:10:45] [Server thread/INFO]: �[0;36;1m | | | / |__/ �[0;36;22m|__) |__ |__) |\/| /__ �[m
[14:10:45] [Server thread/INFO]: �[0;36;1m |___ _/ _, | \ �[0;36;22m| |___ | \ | | .__/ �[m
[14:10:45] [Server thread/INFO]: �[m
[14:10:45] [Server thread/INFO]: �[0;32;22m Loading version �[0;36;1mv4.0.80�[0;32;22m on Bukkit - CraftBukkit�[m
[14:10:45] [Server thread/INFO]: �[0;30;1m Running on server version git-Spigot-db6de12-18fbb24 (MC: 1.8.8) - 1.8.8-R0.1-SNAPSHOT�[m
[14:10:45] [Server thread/INFO]: �[m
[14:10:45] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mLoading configuration...�[m
[14:10:45] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mIdentified the following dependencies: [H2_DRIVER]�[m
[14:10:45] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mLoading storage provider... [H2]�[m
[14:10:46] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mLoading internal permission managers...�[m
[14:10:46] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mPerforming initial data load...�[m
[14:10:47] [Server thread/INFO]: �[0;37;22m�[21m[�[0;36;1mL�[0;36;22mP�[0;37;22m�[21m] �[0;36;22mSuccessfully enabled. (took 1885ms)�[m

Not sure how you've done it, but somehow you've set server to an empty string.

(server=)

Which command did you use to set the prefix?

I used both /lp group warrior meta addprefix 100 " &2(Warrior)" & /lp group warrior meta addprefix 100 " &2(Warrior) skyblock (which is the server)

Try with:
/lp group warrior meta addprefix 100 " &2(Warrior)" skyblock

You were missing a quote on the first example.

If you update to the latest LP version, it will validate those inputs for you.
https://ci.lucko.me/job/LuckPerms/

You forgot the closing quotes in the second command.

Edit: Ninjaed by Luck xD

Still tried it with latest version & the command but still doesn't work:

[18:26:57 INFO]: RareDragon issued server command: /lp creategroup warrior
[18:26:58 INFO]: [LP] LOG > (RareDragon) [G] (warrior)
[18:26:58 INFO]: [LP] LOG > create
[18:26:59 INFO]: RareDragon issued server command: /lp
[18:27:02 INFO]: RareDragon issued server command: /lp group warrior
[18:27:04 INFO]: RareDragon issued server command: /lp group warrior meta
[18:27:26 INFO]: RareDragon issued server command: /lp group warrior meta addprefix 100 " &2(Warrior)" skyblock
[18:27:26 INFO]: [LP] LOG > (RareDragon) [G] (warrior)
[18:27:26 INFO]: [LP] LOG > meta addprefix 100 (Warrior) server=skyblock
[18:27:27 INFO]: RareDragon: Test
[18:27:30 INFO]: RareDragon issued server command: /lp parent
[18:27:37 INFO]: RareDragon issued server command: /lp user RareDragon parent
[18:27:41 INFO]: RareDragon issued server command: /lp user RareDragon parent set warrior
[18:27:41 INFO]: [LP] LOG > (RareDragon) [U] (raredragon)
[18:27:41 INFO]: [LP] LOG > parent set warrior
[18:27:43 INFO]: RareDragon: Test
[18:27:44 INFO]: RareDragon: Test
[18:27:45 INFO]: RareDragon: Test
[18:27:46 INFO]: RareDragon: Test

Ok, that looks like it has applied correctly.

Remaining issue is most likely down to your chat plugin.

Just make sure /lp user <you> info shows the correct value. If that's all good, then you need to tweak your chat plugin to get it to work nicely.

See here for more info with that:
https://github.com/lucko/LuckPerms/wiki/Prefixes,-Suffixes-&-Meta#displaying-prefixes-and-suffixes