Due to recent changes in permissions that blocks the usage of /lb lookups from members (except for /lb tb), it is no longer allowed to use logblock to track dynmap-hidden members. This now means you can not use any command to track members. If they're hidden on dynmap you're out of luck.
Senior members/donators+ will still have access to logblock lookups. This means SM/Don+ is still allowed to use logblock to track other SM/Don+, just not on regular members.