Wake from sleep kinda broken-ish? (ThinkPad Carbon X1 6th gen)

Hi,

ever since I started using my 6th gen ThinkPad X1 Carbon as my daily work horse back in 2019 I have had occasional problems getting it to wake from sleep. Lately I thought I had nailed it down somewhat - making sure I close the lid (which is the only condition in which it will sleep on its own) only while the screen is actually on. Closing the lid when the screensaver had turned the display off would almost certainly prevent waking from sleep.

Now, since I updated from r365358 to r365688, I have not once been able to wake from sleep.

The problem manifests thus: The computer seems to go to sleep correctly; the LED on the display starts pulsating as it should and all fan activity stops. Upon opening the lid, the pulsating stops, but the power LED pulsates instead. There is no display activity and no signs of it actually waking up. Force-power-off is the only way to resuscitate, after which (and I am fairly sure I'm not imagining this) it is very hard to get my GELI password right - so another power cycle is required before the keyboard is fully reliable pre-boot.

I have absolutely no idea how to go about debugging this. The BIOS on the system is pretty new, the TPM chip is disabled (that seemed to help reliability quite a bit), and unused/unsupported devices are disabled in BIOS. No BIOS configuration has changed between the revisions.

Any hints would be more than welcome.

Thanks all,
/Eirik