Rancher 2.5.5 can't upgrade Longhorn app to greater v1.2.6

Running Rancher v2.5.5

I managed to upgrade Longhorn via the longhorn app from version 1.1.x to version 1.2.6 via Cluster UI
( not the new-style Cluster Explorer ).
But now I’m stuck with that version, this is the latest version that Cluster UI shows.
How can I upgrade Longhorn ?

I’ve tried to “refresh” all the catalogs, but Longhorn seems to be stuck in v1.2.6, new newer versions is shown in Rancher Cluster UI.

See github issue 41863.

I known, I’m late in the game ( my used rancher and k8 is outdated ) but I’m in the mids of upgrading rancher / longhorn / k8s.
Any hint or help appreciated !

I upgraded rancher to latest v2.5 version ( v2.5.17 ) and refreshed catalogs - but still UI shows no newer version avail for longhorn.

I managed to upgrade longhorn: