How to use player search?

Hello again new forum. I can't get the search to work, I've played with all of those filters and what not. I found someone to party with on Leviathan and we can't search each other in-game. I can find them just fine on the ffxiv website, and we are both in fact in Leviathan. I had all filters on and off, then specific to the person i'm looking for. I don't know whats going on.

The player search will not display players that are offline. Nor will it display players that are in a duty that involves them traveling to an instance that's not part of Leviathan.

Beyond that, I usually just type "/sea forename " followed by their first name into the chat box.

The game will tell you how to use any command if you use the /? command on it.
Try these:

/? ?
/? search
/? sea