This happened to me after i left the game

The two stations to the right were their "home" stations until they got somewhat disconnected probably due to a chunk unload (and reload)

Robots seem to have a tonne of odd and random issues, especially when it comes to chunkloading. They also don't log anything helpful other than "I just failed to find my home". I haven't changed any of the robot code recently so its unlikely that updating will help.

i'd have to look at the code but is it possible this is chunk loading order issue? where the the robot is initialized but the pipe and docking station are not, if so having the robot wait a few seconds and then try again might fix it

Possibly.

does this still heapen with the latest version? if so can you provide a log of when it heapens to try and trace this?