Tweaking 'Workspaces on primary display only' doesn't change gnome/shell/overrides setting
There are apparently both /org/gnome/shell/workspaces-only-on-primary and /org/gnome/mutter/workspaces-only-on-primary, and tweak tool only changes the latter leading to inconsistent behaviour:
https://github.com/N-Yuki/gnome-shell-extension-workspace-isolated-dash/issues/20