[BroZeus]

TextDrawSetString(Text:LoggedInAs[playerid], string);
there is no need of bold part in the above text
use it as
TextDrawSetString(LoggedInAs[playerid], string);

and also in stock CheckLoggedInAs
why are you setting player's rank after setting the text draw string
first set rank then set string

Well this is not the solution to your problem these are just small mistakes i found

Possible cazes of textdraw disappear are--
-If you choose values for y that are less than 1, the first text row will be invisible and only the shadow is visible.

- If the last character in the text is a space (" "), the text will all be blank.

- If part of the text is off-screen, the color of the text will not show, only the shadow (if enabled) will.