[Nexus 6 Android Development] u_know_me:
Thanks for your quick response chineel, since I've screw up my phone system (due flash facelock all fix), I will start with clean install from the beginning, and report back if trusted face is works or not.

Edit. After clean install, trusted face still missing,

Log of gapps

# Begin Open GApps Install Log

------------------------------------------------------------------

ROM Android version | 8.1.0

ROM Build ID | OPM7.181005.003

ROM Version increment | d087d7fc92

ROM SDK version | 27

ROM/Recovery modversion | 4.7

Device Recovery | TWRP 3.2.1-0-2af13795

Device Name | shamu

Device Model | Nexus 6

Device Type | phone

Device CPU | armeabi-v7a,armeabi

Device A/B-partitions | false

Installer Platform | arm

ROM Platform | arm

Display Density Used | 560

Install Type | Clean[Data Wiped]

Smart ART Pre-ODEX | false

Google Camera already installed | Clean

FaceUnlock Compatible | true

VRMode Compatible | false

Google Camera Compatible | true

New Camera API Compatible | true

Google Pixel Features | false

Current GApps Version | No GApps Installed

Installing GApps Zipfile | /sdcard/open_gapps-arm-8.1-mini-20181013.zip

Installing GApps Version | 20181013

Installing GApps Type | mini

Config Type |

Using gapps-config | Not Used

Remove Stock/AOSP Browser | false[NO_Chrome]

Remove Stock/AOSP Camera | false[NO_CameraGoogle]

Remove Stock/AOSP Dialer | false[NO_DialerGoogle]

Remove Stock/AOSP Email | false[default]

Remove Stock/AOSP Gallery | false[default]

Remove Stock/AOSP Launcher | false[default]

Remove Stock/AOSP MMS App | false[default]

Remove Stock/AOSP Pico TTS | false[default]

Ignore Google Contacts | false

Ignore Google Dialer | false

Ignore Google Keyboard | false

Ignore Google Package Installer | false

Ignore Google NFC Tag | false

Ignore Google WebView | false

Total System Size (KB) | 1998672

Used System Space (KB) | 1042636

Current Free Space (KB) | 918684

Post Install Free Space (KB) | 475488 << See Calculations Below

------------------------------------------------------------------

# End Open GApps Install Log

!!! WARNING !!! - Duplicate files were found between your ROM and this GApps

package. This is likely due to your ROM's dev including Google proprietary

files in the ROM. The duplicate files are shown in the log portion below.

# Begin GApps <> ROM Duplicate File List

/system/app/Tycho

/system/etc/sysconfig/dialer_experience.xml

/system/lib/libjni_latinimegoogle.so

/system/priv-app/CarrierServices

/system/priv-app/GCS

/system/priv-app/Turbo

# End GApps <> ROM Duplicate File List

# Begin GApps Size Calculations

------------------------------------------------------------------

TYPE | DESCRIPTION | SIZE | TOTAL

| Current Free Space | 918684 | 918684

Remove | Existing GApps | + 8448 | 927132

Remove | Obsolete Files | + 924 | 928056

Remove | calculatorstock | + 772 | 928828

Remove | calendarstock | + 2308 | 931136

Remove | clockstock | + 4712 | 935848

Remove | cmsetupwizard | + 0 | 935848

Remove | exchangestock | + 0 | 935848

Remove | extservicesstock | + 20 | 935868

Remove | extsharedstock | + 12 | 935880

Remove | packageinstallerstock | + 5972 | 941852

Remove | provision | + 12 | 941864

Remove | tagstock | + 356 | 942220

Install | Core | - 91164 | 851056

Install | batteryusage | - 1324 | 849732

Install | calculatorgoogle | - 2020 | 847712

Install | calendargoogle | - 19728 | 827984

Install | clockgoogle | - 5688 | 822296

Install | dialerframework | - 12 | 822284

Install | exchangegoogle | - 480 | 821804

Install | facedetect | - 612 | 821192

Install | faceunlock | - 9284 | 811908

Install | gmail | - 22744 | 789164

Install | googlenow | - 8092 | 781072

Install | googletts | - 22708 | 758364

Install | maps | - 33060 | 725304

Install | messenger | - 14224 | 711080

Install | packageinstallergoogle | - 5692 | 705388

Install | photos | - 52188 | 653200

Install | search | - 84684 | 568516

Install | speech | - 39128 | 529388

Install | taggoogle | - 348 | 529040

Install | youtube | - 44336 | 484704

| Buffer Space | - 9216 | 475488

------------------------------------------------------------------

Post Install Free Space | 475488

------------------------------------------------------------------

# End GApps Size Calculations

# Begin User's gapps-config

# End User's gapps-config