App Store not showing recent updates in 10.15.4

Ever since I updated my iMac to Catalina 10.15.4, and even before I applied the Supplemental Update patch, I have received no notifications from the App Store, that I have any updates to any of my existing apps. I saw there were updates posted on the MacUpdate site for Keynote, Numbers, and Pages, but these do not register in the App Store, nor do updates for anything else I got from the Store. I have seen that this issue is an old one, but since it has never happened to me before, I wonder if I may have done something that may have disabled the Store's ability to present updates. I would appreciate any help with restoring this ability, if it is missing.