I have recently have had two different 'incidents', where the 48 hours for being registered as inactive in my guilds memberlist has been wrong.
#1: Online player (green light in guild list/friends list) in Guild interface registered as inactive
#2: A player registered as inactive less than 29 hours than being online
Had completed Guild Quest Day 1, but at Day 2 registered as inactive at 16:17 GMT...
Tickets about both incidents have been submitted to Support with relevant screenshots but they need more information...
If any others (Officers/Leaders) have recognized similar issues please reply so BB will dig into the issue and get it sorted for the benefit of us all
If we don't tell BB the chance of getting it sorted is close to zero.
Update 28.04.17: BB is aware about this topic and DEVs are working on a solution.