FreeOrion

Build 2018-02-25

I have a fleet of troops traveling at 60 that left one of my planets at the same time as two grav hull ships traveling at 100, all for the same destination. The next turn still shows them grouped together (which they shouldn't be), and with the white movement path dots still in the starlane showing where the slower troop ships should be, but without a ship icon there.
On the next turn they separated into the two fleets in the correct locations on the starlane.
Also I have not researched Interstellar Logistics yet so that should not be having an effect.

This issue has been in the game for at least a few weeks but I hadn't realized specifically what was going on before.

Something like this happened to me at least once. The colony ship was damn fast, and not only a problem of wrong displaying because the colony ship actually got to the place (I got the sitrep, I could select the ship orbiting the planet) sooner than other ships with same speed that were en route one turn before the colony ship (I mean, no doubt, that was faster than expected).

Interesting and helpful report. Please set aside a copy of the savegame from the turn right before that, if you still have it, and post it (zipped) along with the screenshot in a Issue on our github repo. There was some recent work done to improve the handling of overlapping fleet-buttons (the fleet icons on the map), and the logic for deciding when to keep them grouped together as they move, and when to make separate buttons, is a bit tricky and apparently in need of some refinement.

I didn't keep that one but here is a similar one; two ships crossing paths in different directions on a starlane, you can see the movement dots where the icon for the Robotic Hull ship should be, instead of combined with the icon for the outpost ship.
The Robotic Hull is heading down past Fehu Y.

Here is the save file:

Did you by any chance change your zoom level significantly after initially selecting the fleets?
Never mind that question, I asked after thinking about the issue some, but then I decided I had time to open and check the savegame myself, and see that the issue has nothing to do with changing zoom after selection.

just to note here, I've opened an Issue for this on github. If anyone gets any more clues about when in particular this happens, etc., please add to that issue (or at least post here).

Another report of the same thing.
Battle Fleet 6912 is actually where the red arrow is pointing to. I could not select it directly, but I could just click on the displayed fleet icons (either the red one, monsters, or the green one that is incorrectly amalgamating the two battle fleets, the unnumbered one and the 6912) and the GUI will appropriately cycle over the three fleets. So even if the amalgamations was not there and the three fleets were all exactly on top of each other, I could still select any one of them.

That makes me wonder if the recently added mechanic to amalgamate fleets to help selecting them is actually unnecessary? When this was requested it was stated that the flee falling under another fleet button could not be selected by any means, but in this case I can select it even by clicking on the red icon (Monster) fleet a couple of times.
If the new mechanic is what allows for this "click over it until the fleet you want is selected", I would suggest to remove the part of code that amalgamates fleet buttons and leave only the part that allows for the cycling over nearby fleets. Otherwise I would just revert the whole change.