Simples... the user has not been active since the migration to Microcosm and on vBulletin had marked their profile as "invisible" so that you couldn't browse the "Who's Online" bit and stalk them.
In vBulletin, marking yourself invisible stopped updating the "Last Active" column.
In Microcosm we do not have "Who's Online" so everyone has more privacy and there is no need for the "Invisible" mode. We also only show "Last Active" down to a 24 hour period rather than to the second (like vBulletin did) so it doesn't matter that we keep it up to date.
In vBulletin Last Active = last time you viewed a page or logged in whilst not invisible, displayed via Who's Online down to the second.
In Microcosm Last Active = last time you interacted as a logged in user with any part of the system, but only displayed as a 24 hour period.
Reading that carefully, you'll notice that vBulletin doesn't update Last Active if you post whilst invisible. This makes sense for them, you could be posting in a private forum on vBulletin and don't want to leak that info via Last Active. Hence, being invisible on that version of vBulletin didn't update the value.
In essence: Microcosm is correct, but values from before the migration to Microcosm may be off if the user had invisible enabled and hasn't used the forum since the migration.
Simples... the user has not been active since the migration to Microcosm and on vBulletin had marked their profile as "invisible" so that you couldn't browse the "Who's Online" bit and stalk them.
In vBulletin, marking yourself invisible stopped updating the "Last Active" column.
In Microcosm we do not have "Who's Online" so everyone has more privacy and there is no need for the "Invisible" mode. We also only show "Last Active" down to a 24 hour period rather than to the second (like vBulletin did) so it doesn't matter that we keep it up to date.
In vBulletin Last Active = last time you viewed a page or logged in whilst not invisible, displayed via Who's Online down to the second.
In Microcosm Last Active = last time you interacted as a logged in user with any part of the system, but only displayed as a 24 hour period.
Reading that carefully, you'll notice that vBulletin doesn't update Last Active if you post whilst invisible. This makes sense for them, you could be posting in a private forum on vBulletin and don't want to leak that info via Last Active. Hence, being invisible on that version of vBulletin didn't update the value.
In essence: Microcosm is correct, but values from before the migration to Microcosm may be off if the user had invisible enabled and hasn't used the forum since the migration.