howdy does not recognize my face anymore

[orclex]

since upgrade to howdy 2.6.1 (kubuntu 20.04) it does not recognize my face anymore.

To be sure it should recognize my face I add a new model

# howdy add
NOTICE: Each additional model slows down the face recognition engine slightly
Press Ctrl+C to cancel

Adding face model for the user alex
Enter a label for this new model [Model #27] (max 24 characters): 

Please look straight into the camera
Scan complete

Added a new model to alex

I did not move my face and tried to authenticate via sudo afterwards:

$ sudo su
Face detection timeout reached
[sudo] Passwort für alex: 

howdy config is:

[core]
detection_notice = false
no_confirmation = true
suppress_unknown = false
ignore_ssh = true
ignore_closed_lid = true
disabled = false
use_cnn = false

[video]
certainty = 1.5
timeout = 4
device_path = /dev/v4l/by-path/pci-0000:00:14.0-usb-0:8:1.2-video-index0
max_height = 320
frame_width = -1
frame_height = -1
dark_threshold = 50
recording_plugin = opencv
device_format = v4l2
force_mjpeg = false
exposure = -1

[snapshots]
capture_failed = true
capture_successful = true

[debug]
end_report = false

Any hints to debug this?

[orclex]

Sometimes I got a mesage that images are too dark (normal room light, that worked before).

$ sudo su
All frames were too dark, please check dark_threshold in config
Average darkness: [75.13589], Threshold: 50.0
Face detection image too dark
[sudo] Passwort für alex:

I changed _darkthreshold to 100 but I still get a timeout and no message about too dark frames:

$ sudo su
Face detection timeout reached
[sudo] Passwort für alex: 

[FredyVia]

I tried another method : that is, during installation when I choose whether IR works, I found that the installer will try there methods to drive the IR camera. My IR camera lights up in both cases, but in the first case,after run sudo howdy test the image is almost all dark(99).So I tried the second one and found that it works well. By the way, my computer is Lenove Xiaoxin Pro 13