System updates not appearing? Just press Cmd + R!

[Apple Knowledge Navigator]

Not sure if this is common knowledge (I'm only guessing it isn't), but if you didn't already know, you can 'refresh' the Software updates screen in System Settings simply by pressing Cmd + R.

Handy for forcing the system to check!

 

[bogdanw]

I would say it's pretty well known, as it's in the manual.
"Command-R: (1) When an alias is selected in the Finder: show the original file for the selected alias. (2) In some apps, such as Calendar or Safari, refresh or reload the page. (3) In Software Update, check for software updates again."
https://support.apple.com/en-us/102650
Anyway, Apple has added a Check for Update button in Sequoia 15.4