Who Me Too'd this topic

SETUP: PALO ALTO connected to ACTIVE DIRECTORY for groups
CAPTIVE PORTAL ACTIVATED 
idle time-out 500minutes
timer: 600minutes

CLI> show user ip-user-mapping ip x.x.x.x

SCENARIO 1: 
user log in to PC > mmp1234
CLI> show user ip-user-mapping ip 1.2.3.4.
Ip address: 1.2.3.4
User: mmp1234
From: UIA
idle-timer:3000s (3k)

SCENARIO 2: 
after logging in to PC, user will now login to CAPTIVE PORTAL
CLI> show user ip-user-mapping ip 1.2.3.4.
Ip address: 1.2.3.4
User: mmp1234
From: CP
idle-timer:30000s (30k secs  = 500minutes)

PROBLEM:
After 15minutes or more, 
CLI> show user ip-user-mapping ip 1.2.3.4.
Ip address: 1.2.3.4
User: mmp1234
From: UIA
timer:3000s

QUESTION>
Why is it changing to UIA? I want CP to remain for 500minutes or 600minutes without any disturbances.

NOTE> 
I am sure that this user does not login on any other PC.