You have items ready to install (segment-leaders) every sync in Garmin Express

Yes, virtually every boot up of my device has the segment lists updating (deleting and downloading).  I figured this was just reflecting the fact that the various targets that the Edge can report on can change so the device updates them when new data is available.

In my case it happens even when I hit refresh immediately after installing these updates

Ah I see what you mean.  I rarely hook my device up to computer/Garmin Express.  But practically every time I boot my device up and it links up with my phone/Garmin Connect app, it goes through a cycle of downloading and deleting segments.  

This is happening to me as well on my 520 Plus. Ever come up with a solution? 

I'm not sure there is anything to solve? To me it is working as intended, segment leaderboards are constantly changing and so the device gets updated with those changes. It is still a regular occurrence for me.