Since updating to 10.11.5 on all my machines (not that I think that's necessarily the cause--just a correlation) I'm seeing a weird issue whereby any MAS-purchased apps are not showing updates in the updates tab (I get the "No Updates Available" banner). These are apps which I know for a fact have been updated and the app store shows newer version numbers than what I have installed. It affects all apps, as far as I know. When I visit those apps' pages in the app store the button says "OPEN" rather than "UPDATE". I first experienced this issue a couple of weeks ago and it persists even through today. I've tried signing out and back into my Apple ID in the app store app (also I only have one Apple ID and have used to that to purchase all of my apps), and also tried force quitting the app along with the softwareupdated service--no change at all. The only talk about this issue I've found online was an issue with Yosemite involving having added the boot volume to Spotlight exceptions (not the case here--I have nothing in the Spotlight exceptions list). The only thing that does work is rebooting. After I reboot and log back in, the App Store Updates tab will suddenly show all the app updates which it previously was not. I can install them and everything's great, until x amount of time later, the same thing happens. I would suspect some sort of local corruption issue, except that this is happening in exactly the same way on TWO different Macs--a 13" 2013 MBPr and a 13" 2011 MBA. Given that there is no widespread discussion about this problem, my best guess is that the cause is some app I have installed on both Macs which is breaking the App Store update mechanism. But short of deleting apps at random one-by-one I'm not sure of another way to troubleshoot this. The biggest problem with manually troubleshooting is I'm dependent upon new app updates actually being released to see if the app store updates tab shows them (and I don't have enough Mac apps to have that be a daily occurrence. I'm lucky if there is one app update available every week). So is there anyone out there who knows enough about what triggers MAS update notifications that can help me figure out if there's a specific service I need to get logs for to help figure this out? At a minimum is there a specific service I can kill and restart as a temporary fix rather than rebooting the whole machine? Much appreciate any ideas.