The bug: When given a "move" command, fleet members start accelerating towards their destination sector. Once they reach it, the do not break, but start drifting instead. This results all the members to miss specified sector and enter the neighboring one.
Not to mention I am still waiting for any progress on T2301, T1249, T2011 (closed as a duplicate, while visually being completely separate problem), this bug with "move" command renders fleets even more unplayable.