Check permission of offline/sleeper player?

In lua, is it possible to check if an offline player (in group "player") has a permission or not? When trying "permission.UserHasPermission" it always returns false even though the group "player" has the flag im checking for and the player is in the group. Thanks.

 

Loop through all sleepers.
Find the sleeper steamid
and then if permission.UserHasPermission(sleeperSteamId, "admin") then

 

I do loop and obtain the steamid of the player. No matter what I try, it always returns false.

 

You can loop through oxide.users.json

 

That is a good idea but, I decided to restart the server, and permission.UserHasPermission seems to work just fine now. When granting or revoking permissions for a player only, the json file is updated but the plugin doesn't notice the change until the server is restarted. The player im testing on is offline if it makes a difference. If I change a permission to the admin group, and im online, it works just fine. Changing the players group doesn't work.

Edit: Everything seems to work as expected now... I won't even pretend to understand whats happening. :\