Not sure if this is a bug or intentional to de-highlight them…
I think this is intended and I also like this feature, makes it easier to spot which fleets are on loop and which are not if there are multiple fleets on voyage between the same stars. But sure this is sometimes problematic if there are too many fleets around.
This is not a bug.
Ditto - I find this a handy visual aid along with the dashed lines.