[BUG] Index HMD display not detected after each reboot

[DASPRiD]

Describe the bug Since 3 or 4 days I'm running into the problem that the Index HMD is not detected after a reboot. So when I'm starting SteamVR, the HMD output is just displayed on the main monitors. I always have to re-plug the Index on the breakaway cable to make SteamVR detect it.

Expected behavior The HMD should always be directed without the need to re-plug it.

System Information (please complete the following information):

• Distribution: Pop_OS! 20.04
• SteamVR version: 1.13.10 (beta channel)
• Steam client version: Jul 10 2020, at 21:43:18
• Opted into Steam client beta?: No
• Graphics driver version: NVIDIA 440.100
• Gist for SteamVR System Information: https://gist.github.com/DASPRiD/1f50420d25ee21b20272f1a586ec5243

Note: Commenters who are also experiencing this issue are encouraged to include the "System Information" section in their replies.

I'm also not 100% sure if this a bug of SteamVR or of the NVIDIA driver. Once I re-plug the HMD, I get the following output in the syslog, which does not appear at boot time:

/usr/lib/gdm3/gdm-x-session[2636]: (--) NVIDIA(GPU-0): DP-0: Found Head Mounted Display; ignoring for use in X.  See
/usr/lib/gdm3/gdm-x-session[2636]: (--) NVIDIA(GPU-0):     the 'AllowHMD' X configuration option for details.
/usr/lib/gdm3/gdm-x-session[2636]: (--) NVIDIA(GPU-0): DFP-1: disconnected
/usr/lib/gdm3/gdm-x-session[2636]: (--) NVIDIA(GPU-0): DFP-1: Internal DisplayPort
/usr/lib/gdm3/gdm-x-session[2636]: (--) NVIDIA(GPU-0): DFP-1: 2660.0 MHz maximum pixel clock

[yaomtc]

This has been happening to me but it's also been affecting my display manager SDDM. Possibly related: https://github.com/sddm/sddm/issues/1893