How come the UC doesn't tell someone about the v4 versions via the "Check for Updates" if they are on the latest v3 version?

Details:
I have a client on v3 of the UC for the Revelator io24.

When they choose "Check for updates" it says they are up to date.

I have to tell them "That's bogus... the UC is now two generations into v4..."
Go download 4.x manually on the Presonus site.

People who try to stay current (many of my clients) don't realize there has been an update, even when they do the right thing and use the software to check.

What are we missing?

(This behavior makes some sense for S1, where there is an upgrade charge, but I'm unclear why that same behavior applies to the UC... which is always free...)