No wi-fi adapter found in Ubuntu 18.04, it was working properly before but stopped working yesterday, Intel Wireless 8260 adapter

QUESTION UPDATED

I have a dual boot with Ubuntu 18.04 and Windows 10. Wifi was working fine until two days ago, and it stopped working for no apparent reason. Wifi in Windows 10 is working fine.

There has been some developments in the question above and the problem itself changed. In my Asus Zenbook, I had originally disabled Secure Boot, but when this problem started to happen I realised that it was enabled again. As mentioned in the previous question the behaviour of Ubuntu recognising the card was quite erratic. However, there was in the BIOS an option called Secure boot control which was enabled. I don’t know what it means, but I disabled it and the erratic behaviour disappeared.

Since then, the wifi adapter is still not working, but lshw always gives the following message:

sudo lshw -c network
  *-network UNCLAIMED       
       description: Network controller
       product: Wireless 8260
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:02:00.0
       version: 3a
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress cap_list
       configuration: latency=0
       resources: memory:ef000000-ef001fff

Other commands:

lspci -nnk | grep 0280 -A3
02:00.0 Network controller [0280]: Intel Corporation Wireless 8260 [8086:24f3] (rev 3a)
    Subsystem: Intel Corporation Wireless 8260 [8086:0110]
    Kernel modules: iwlwifi

sudo modprobe iwlwifi && dmesg | grep iwl
[    3.626468] iwlwifi 0000:02:00.0: Refused to change power state, currently in D3
[    3.626772] iwlwifi 0000:02:00.0: HW_REV=0xFFFFFFFF, PCI issues?
[    3.651088] iwlwifi: probe of 0000:02:00.0 failed with error -5

sudo rfkill list all
0: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no

sudo modinfo iwlwifi | grep 24F3 | grep 0050
alias:          pci:v00008086d000024F3sv*sd00000050bc*sc*i*

I have the following kernel, updated yesterday (Ubuntu is 18.04.4):

uname -a
Linux arbexzen 5.3.0-62-generic #56~18.04.1-Ubuntu SMP Wed Jun 24 16:17:03 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux