I just encountered an issue related to this in elementaryOS 6 (Odin). The Alt+Shift shortcut for switching keyboard layouts was interfering with the default Alt+Shift+Tab shortcut for cycling backwards in the window switcher.
Disabling or changing the Switch layout shortcut did the trick for me.
Worked for me like this
edit the alsa.conf
sudo nano alsa.conf
add the following line to the options section
options snd-hda-intel dmic_detect=0
the ** out of that file. and it updates. im sure you have already been installing all the software already. try it in reverse ...
I am on Hera - Elementary 5.1.
Tried many ways. This is the only way working for me.
None of the above solutions work at the moment. Following method works fine (tested in elementary OS 6 ODIN and OS 5).
Full guide: https://www.debugpoint.com/2021/07/change-lock-login-screen-background-elementary-os/
Open a terminal in your elementary OS.
Install git and following dependencies for greeter package.
sudo apt install git
sudo apt install -y ...