Sharing this here as I’ve wasted a lot of time searching in the past and again recently on a fresh install.
Lock screen is disabled by default. Perhaps this was configured as there were issues with locking in the past. Use dconf-editor to enable. Screenshot:

Sounds like a bug - I’d suggest reporting it via bugzilla to ensure that this is corrected.
What version of Tumbleweed did you install? (the ISO name will include the version - or you can find it in /etc/os-release
as the VERSION_ID
value (for example, my installation is VERSION_ID="20230512"
, but it’s been upgraded constantly since the initial installation in September of last year).
I created the ISO from another machine, so I don’t have it offhand. It was the latest release from ~1-2 months ago. I had this problem on years ago though as well, so I suspect it wasn’t a recent change.
I will report on Bugzilla.
Sounds good. It’s possible it could have been a regression as well - something that was fixed and then a subsequent fix reverted.