final cut pro not updating

Is anyone having issues getting the Final Cut Pro X update 10.4.10 to install on Mojave 10.14.6?

I am seeing an update for FCP X plus two related apps in the AppStore. The Update button and Update All links are active, but clicking on them does not result in the updates downloading. I see a spinning icon for a little, then the app store reverts to showing the three apps with active Update buttons.

Clicking through to the app page, I have the exact same problem - it will not update at all.

I did install the Security Update that appeared before the weekend and I've restarted several times since.

Possibly related: is there an issue with that Security Update? My iMac has been taking its sweet time with disk access operations every since I did that.