Cfxtrjtrk

I recently noted that my Thinkpad X1 Yoga (1st Generation) will not enter the suspend mode any more when I close the lid of the notebook.
I updated from Ubuntu 18.04.2 to 18.10 recently but I am not 100% sure if the error occured right after the update.
What I have checked:

(1) I checked that my /etc/default/grub was not changed since I last configured it:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

(2) I changed the /etc/default/grub following this hint (no effect):

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi_sleep=nonvs"

(3) I changed /etc/systemd/logind.conf to the following. I edited the Inhibit-entries to "yes" (no effect):

[Login]

HandlePowerKey=hibernate

HandleHibernateKey=hibernate

HandleSuspendKey=suspend-then-hibernate

HandleLidSwitch=suspend-then-hibernate

HandleLidSwitchDocked=suspend

PowerKeyIgnoreInhibited=yes

SuspendKeyIgnoreInhibited=yes

HibernateKeyIgnoreInhibited=yes

LidSwitchIgnoreInhibited=yes

(4) I thought about the sleep mode itself being broken. But executing sudo pm-suspend in terminal will correctly initiate the suspend mode. The screen is getting dark and the power LED is flashing after a few seconds.

(5) I checked if the lid sensor itself is broken. Since the Thinkpad uses a magetic sensor in the base and has a magnet in the lid, I tried to trigger the sensor with an external magnet. The sensor seems to work. When moving the magnet over the sensor, the screen turns black. But nothing else happens, the power LED is still on. When removing the magnet, the screen is on again.

(6) (update) I also tested sudo pm-suspend-hybrid to check if the hybrid suspend mode is broken. This was not the case. The machine entered the suspend mode as expected (screen black + Power led flashing

(update) free -h gives the following output:

           total        used        free      shared  buff/cache   available

Mem:       7,2Gi       1,7Gi       3,7Gi       674Mi       1,8Gi       4,6Gi

Swap:      9,0Gi          0B       9,0Gi

Do you have any more ideas how to get the suspend mode working again? I would like to trigger the new suspend-then-hibernate mode on lid close.

After performing another Core update for Ubuntu, it is working again.

It seems like there were modifications on the suspend mode or in one of the drivers. I checked the release notes for Ubuntu 18.10 and found nothing, but it looks like there were changes anyway.