I need to update longhorn but it was installed on old Rancher Apps and then moved to a different instance of Rancher, so it doesn’t appear under “Apps” anymore. Any ideas are greatly appreciated.

Does this help? https://longhorn.io/kb/how-to-migrate-longhorn-chart-installed-in-old-rancher-ui-to-the-chart-in-new-rancher-ui/

Ooh that might be what I’m looking for, thanks very much I’ll have a look!