Follows are what happens:

You launch a fleet on routine FS
--> The browser proceeds from fleet III page to fleet movement view
--> You hit [Enter] to go to fleet I
--> The browser proceeds to fleet I page of the "next" planet/moon instead of where you were,

where "next" is in the sense of "next planet / next moon" button in the right pane.

As far as I have seen, this occurs only when you're in the fleet movement view after launching a routine FS mission. No "&cp=..." query string is contained in the URL after proceeding to the fleet I page.

I see. Actually I make it a rule to check to see if there are any ships / resources left sitting by mistake every time I FS, using the press-enter-to-go-to-fleet-I feature. Now it's gone but all I have to do is to go back to the original place manually. Not a big problem. Thx.