Comment 16 for bug 1812387

Confirmed. LXD repro instructions:

$ lxc launch ubuntu-daily:cosmic tester && lxc exec tester bash

# apt update && apt dist-upgrade -y && apt install -y tmux tmux-plugin-manager &&
ulimit -c unlimited &&
cat << 'EOF' >"$HOME/.tmux.conf"
# set prefix: Alt + e
set -g prefix M-e
# Let's bind this too, so that repeated
# presses work, esp. when nesting.
bind -n M-e send-prefix

# start window numbering at 1
set -g base-index 1
# start pane numbering at 1
set -g pane-base-index 1

# use mouse
set -g mouse on
setw -g mode-keys vi

# Use Alt-arrow keys WITHOUT PREFIX KEY to switch panes
bind -n M-Left select-pane -L
bind -n M-Right select-pane -R
bind -n M-Up select-pane -U
bind -n M-Down select-pane -D

set -g @scroll-down-exit-copy-mode off
set -g @scroll-without-changing-pane on
set -g @emulate-scroll-for-no-mouse-alternate-buffer on

# plugins
set -g @plugin 'tmux-plugins/tpm'
set -g @plugin 'tmux-plugins/tmux-sensible'
set -g @plugin 'tmux-plugins/tmux-resurrect'
set -g @plugin 'tmux-plugins/tmux-continuum'
set -g @plugin 'tmux-plugins/tmux-copycat'
set -g @plugin 'tmux-plugins/tmux-pain-control'
set -g @plugin 'tmux-plugins/tmux-prefix-highlight'
set -g @plugin 'tmux-plugins/tmux-open'
set -g @plugin 'tmux-plugins/tmux-yank'
set -g @plugin 'nhdaly/tmux-better-mouse-mode'
set -g @plugin 'tmux-plugins/tmux-logging'

run -b "/usr/share/tmux-plugin-manager/tpm"
EOF

# tmux

* Press alt-e, then shift-i
* exit immediately:

# exit
# tmux

* Press alt-e, then shift-i

Result:

root@tester:~# [lost server]
                            root@tester:~#