Connectors break on entering the physics bubble. #258
When approaching a vessel that has KAS links active, in particular to another vessel, the links break (with a suitable message). I suspect this is because one end of the link is unpacked while the other end of the link is still packed. The breakage itself is only mildly annoying; the big problem is that the KAS.JS1 from which the link broke is itself broken and can no longer be used without editing the save file to reset its connected state.
Also, one possible solution to the link breaking is to have link endpoints force the vessel on the other end of the link to unpack when the endpoint's vessel unpacks. This should not be problematic in general as the default minimum distance between unpack and pack ranges is 150m. Only long chains of connected vessels would potentially cause problems (pack/unpack cycles).
However, the main problem is KAS.JS1 "permanently" breaking.
Also, when loading the scene (via distant vessel switching or from a quicksave), the links seem to be fine.