ChromeOS version: 69.0.3497.95 (Official Build) (64-bit) 
ChromeOS device model: Asus Chromebook Flip C302 cave
Case#: 16892202

Description:
the device doesn't go to sleep after the policy set time (15 min).

Steps to reproduce: 
It's not happening on all customer devices but only on some of them.

Current Behavior / Reproduction: 
Devices won't sleep after 15 Min

Expected Behavior: 
Devices go to suspend/sleep after 15 Min as written in the policy.

In the log I see a change from 15m to 30m:
[1008/095558:INFO:state_controller.cc(916)] Updated settings: dim=0s screen_off=0s lock=0s idle_warn=0s idle=15m (suspend) lid_closed=no-op use_audio=1 use_video=1 wake_locks=
[1008/095559:INFO:daemon.cc(1095)] Received updated external policy: ac_dim=0s ac_screen_off=0s ac_lock=0s ac_idle_warn=0s ac_idle=15m battery_dim=0s battery_screen_off=0s battery_lock=0s battery_idle_warn=0s battery_idle=15m ac_idle=suspend battery_idle=suspend lid_closed=no-op use_audio=1 use_video=1 presentation_factor=2.0 user_activity_factor=2.0 wait_for_initial_user_activity=0 force_nonzero_brightness_for_user_activity=1 (Prefs)
[1008/095559:INFO:state_controller.cc(916)] Updated settings: dim=0s screen_off=0s lock=0s idle_warn=0s idle=15m (suspend) lid_closed=no-op use_audio=1 use_video=1 wake_locks=
[1008/095603:INFO:suspend_delay_controller.cc(121)] Unregistering suspend delay 75563009 (chrome) due to D-Bus client :1.15 going away
[1008/095603:INFO:suspend_delay_controller.cc(121)] Unregistering dark suspend delay 75595777 (chrome) due to D-Bus client :1.15 going away
[1008/095605:INFO:suspend_delay_controller.cc(62)] Registering suspend delay 75563012 (chrome) of 5000 ms on behalf of :1.55
[1008/095605:INFO:suspend_delay_controller.cc(62)] Registering dark suspend delay 75595779 (chrome) of 5000 ms on behalf of :1.55
[1008/095606:INFO:daemon.cc(1077)] Chrome is using presentation display mode
[1008/095606:INFO:daemon.cc(741)] D-Bus org.chromium.DisplayService ownership changed to :1.55
[1008/095606:INFO:display_power_setter.cc(81)] Asking DisplayService to turn internal display off and external displays on
[1008/095608:INFO:daemon.cc(1095)] Received updated external policy: ac_dim=7m ac_screen_off=7m30s ac_lock=0s ac_idle_warn=0s ac_idle=30m battery_dim=5m battery_screen_off=5m30s battery_lock=0s battery_idle_warn=0s battery_idle=6m30s ac_idle=suspend battery_idle=shutdown lid_closed=shutdown use_audio=1 use_video=1 presentation_factor=2.0 user_activity_factor=2.0 wait_for_initial_user_activity=0 force_nonzero_brightness_for_user_activity=1 (Prefs)
[1008/095608:INFO:state_controller.cc(916)] Updated settings: dim=14m screen_off=14m30s lock=0s idle_warn=0s idle=37m (suspend) lid_closed=no-op use_audio=1 use_video=1 wake_locks=
[1008/095608:INFO:daemon.cc(1095)] Received updated external policy: ac_dim=0s ac_screen_off=0s ac_lock=0s ac_idle_warn=0s ac_idle=15m battery_dim=0s battery_screen_off=0s battery_lock=0s battery_idle_warn=0s battery_idle=15m ac_idle=suspend battery_idle=suspend lid_closed=suspend use_audio=1 use_video=1 presentation_factor=2.0 user_activity_factor=2.0 wait_for_initial_user_activity=0 force_nonzero_brightness_for_user_activity=1 (Prefs)

this change is not caused by any changes server side as far as I can see.

ChromeOS version: https://drive.google.com/open?id=1NDX89IijhBH8xbsD1p7srqkGKauAxoJp
Policy: https://drive.google.com/open?id=1cDgw091WdQsIp-POLXwVqiblnhs0CasI

Drive link to logs: https://drive.google.com/open?id=1P3y5Xd4b8D5VCfj5o-XTGLjtjoC48lb3

Customer info: https://docs.google.com/document/d/1rLTLtmkPO1NebiNsINSjBm2eQFsPKRo8PlysuTNlOzQ/edit?usp=sharing