[connork]

You can fix it using a hook.

pawn Code:

forward SendClientMessageEx(playerid, color, const message[]);
public SendClientMessageEx(playerid, color, const message[]) {
    new messagef[256];
    format(messagef, (256), "%s", message);
    if(strlen(message) > 0)
    {
        format(messagef, (256), "%s", \
        str_replace("%", "%%", messagef));
    }
    else format(messagef, (256), "%s", " ");
    return SendClientMessage(playerid, color, messagef);
}

#if defined _ALS_SendClientMessage
    #undef SendClientMessage
#else
    #define _ALS_SendClientMessage
#endif
#define SendClientMessage SendClientMessageEx