Idly going for full destruction on a completed map, I had a few ships multi-selected, and had one outline over the Void off the right of the map. The other two attempted to cluster on the left half of the map. The positions moved in sync. with the main outline, though offset by the width of the map.
Outlines off the left edge had no such behavoiur. N/S had a similar strangeness, I don't recall which edge did what.
This may relate to some people's Doppels trying to head for the next map. I haven't taken a screenshot, because it seemed likely to be trivially reproducible.
I think part of the problem in my instance was that Doppels/ Blue ships can overlap with your ships*.They wanted to go right, but since there was no space they kept going right instead of moving somewhere else.
* When a blue ship/doppel starts moving to a certain spot, move your ship to that same spot and they will overlap.