Here we go again - software update available (not)

I have struggled with this for over a year now. App Store on my MacBook Pro shows an upate available - but there isn't actulaly. It all starts with a flag on the icon in the dock - but when I click on it, then the software updates tab - it will spin and spin, then show nothing (but still say there is one update availabe. Once this behavior begins, it is only a matter of time (usually days) until it will show that there is an update available, and again clicking on it, then the update tab, brings me to the page, but will show a piece of software (for me - it is ALWAYS Twitter app) - and shows that it is installed already (see window capture).

Over the last year, I have done more things than I can remember to make it quit this - from deleting Twitter, then installing it again through the App Store. That doesn't remove it.

I have deleted the App Store prefs... no effect.

I read on another similar thread of resetting the App Store - and followed those directions, which ended the bad behavior for a few weeks, only to return.

In my most recent reappearance of the issue - it showed 1 Update for just over a week - but no actual software listed... until yesterday when there was an update that involved Java. I had it update that... and then Twitter showed up (though it doesn't actually need updating).

Apple is losing its "user-friendly" reputation for many reasons - and bugs like this reflect just one of them.