I know this is old but it’s the most relevant result in my search result, and this answer may help someone else.
It seems that running fwconsole ma showupgrades in the console will actually get it to really check, and then you can run fwconsole ma upgradeall to get the updated modules. This worked for me after a lot of frustration including rebooting the system entirely not getting the web UI to show any available updates after clicking ‘check online’.
See also this thread: Licensed commercial module not fetching updates