The log in comment #5 says that gnome-shell has crashed in the past. In a Xorg session you might not notice when that happens but app windows might then go under the dock when the dock and shell restarts.
Please:
1. Look in /var/crash for crash files and if found run:
ubuntu-bug YOURFILE.crash
Then tell us the ID of the newly-created bug.
2. If step 1 failed then look at https://errors.ubuntu.com/user/ID where ID is the content of file /var/lib/whoopsie/whoopsie-id on the machine. Do you find any links to recent problems on that page? If so then please send the links to us.
The log in comment #5 says that gnome-shell has crashed in the past. In a Xorg session you might not notice when that happens but app windows might then go under the dock when the dock and shell restarts.
Please:
1. Look in /var/crash for crash files and if found run:
ubuntu-bug YOURFILE.crash
Then tell us the ID of the newly-created bug.
2. If step 1 failed then look at https:/ /errors. ubuntu. com/user/ ID where ID is the content of file /var/lib/ whoopsie/ whoopsie- id on the machine. Do you find any links to recent problems on that page? If so then please send the links to us.