Hi,
do you see the update with this command :
fwupdtool get-updates -vv
?
i did these commands to get it to work:
i may be wrong, but i think i had to stop the service then start it back up, to get it to work,
i think removing the cache when the service is stopped may help.
edit seems copying the link messed up the content on here, but the source is ok.