I think the 1.15.5 update was issued to fix the auto syncing of flight logs. When I was on 1.15.4 my flight logs no longer auto synced but now that is fixed in this new update.
I had 1.15.1, and in the iOS app store, it didn't offer an update. If you drag down on the screen, it refreshes the list and THEN it noticed I needed to update 32 apps!
Like ... how often does the app store app refresh?! That's weird.