How to Troubleshoot a Player Who Cannot Use a Command or Feature

Confirm the permission node

The first step is knowing the exact node the plugin or mod checks. Check that plugin's documentation or config. Guessing wastes time — a wrong node will always return false no matter what you grant.

Check what the player actually has

Run /lp user <name> permission check <node>. LuckPerms reports whether the result is true or false and which group or user entry supplied it. If it says false with no source, the node is simply not granted anywhere. If it says true but the feature still fails, the problem is likely elsewhere (plugin config, world context, or another plugin overriding).

Inspect the full map

Use /lp user <name> permission info to dump every effective permission. Look for a false entry that is overriding a true one — a higher-weight group or a direct user node may be denying it. Direct user nodes beat group nodes, and higher weight beats lower weight.

Fix and resync

Grant the node with /lp user <name> permission set <node> true, or add the correct parent group. Then run /lp sync or have the player reconnect so the cache refreshes. If it still fails, temporarily grant * to the player to test whether permissions are the issue at all; if the feature works with *, you have a node-name problem, not a LuckPerms problem.