@Mathieu-L
linstor n l was included in my original post.
All nodes were updated to May 2026 Security and Maintenance Updates for XCP-ng 8.3 LTS, all nodes were restarted.
May 2026 Updates #2 for XCP-ng 8.3 LTS was released, and a couple days later I installed on all hosts. No host restarted.
When xen04 was restarted, that is when this issue happened.
I had used systemctl restart linstor-controller here (https://xcp-ng.org/forum/post/105309) to restart the controller.