Have you tried wiping your cache partition on your device? This is always a good idea after installing an update. This process requires you to restart your device, but will not wipe any data, other than temporary files.
I have a worse issue: it wiped my sim card and unregistered my cell phone. I can only do wifi calling here at home. I am ordering a new sim card for my A12. So ticked off right now.
I don't know if anyone saw the warning before going ahead with the install but it said you could not "roll back" to the previous version of the mobile OS. Really really not happy.