As of LuckPermsSponge-2.15.3.jar, when using /lp from ingame, there's no hint that it needs to be run from console.

The command simply doesn't exist for in-game users.

The only way you'd even find out about the command is by reading the Migration/Command Usage wiki pages, both of which indicate that the commands must be used from the console.

https://github.com/lucko/LuckPerms/wiki/Command-Usage#super-secret-console-commands
https://github.com/lucko/LuckPerms/wiki/Migration#how-to

So, the behaviour is just the same as if you typed in any other unknown command. 🙂

yes, the issue is actually generic:

• in game, any unrecognized command returns the plugin version with no hint that there's an issue.
• in console, any unrecognized command returns the plugin version and a list of commands to use.
  So, in console, it's pretty clear the command is invalid, while in game it's far from obvious.

well, I'm OP and in the admin group imported from Pex.
It appears that I have no perms to use any LP commands because

"permissions-default": 1,

from Pex admin group wasn't migrated to Pex permissions.
As discussed on Discord, the fix is:
/lp group group permission set * true

With that I can see the accessible commands.
So, 1 bug and 1 improvement here:
1- default perms are lost when migrating from Pex
2- when user has no lp perms, show an appropriate message

No usage messages = no access to any LP commands. Again, this goes back to the migration thing, I can't automate everything.

Default perms on PEX behave differently to LuckPerms' wildcard - which is why I'm reluctant to migrate it.

Not sure what you mean. The behaviour re: unrecognised commands is the same for Players/console.

It however, only returns the commands a player has permission to use.