There are periodic reports of intermittent failure to dock, in various threads, with no conclusive explanation. One cause mentioned is running out of charge just before docking, which is odd when so close -- not too sophisticated. I cannot reproduce the problem at will to analyze anything, but there are some msgs listed for the USB command GetLifeStatLog dump related to returning to base. The alert entries will not display on the LCD, only errors. Included in numerous msgs from the laser is one labeled "sunblind", so maybe there is something to the observation about windows. I saw this entry in a partial dump I looked at. Other msg types:
There is no alert for intruders.
Haven't seen any reported log entries after a failure to dock, so I don't know if any of these might indicate something when it happens.
One would guess there is some software error involved in this intermittent failure, but hard to say what. Improperly estimating the reserve charge for base return could be one area, as well as too dumb a docking algorithm. It's been observed that when it backs into the charger incorrectly, it doesn't retry for example, in contrast to very aggressive cleaning behavior with obstacles. Someone mentioned docking terminated by bumping an obstacle it could usually go around. There is an old thread on a serious problem with poor contact with the base plates causing heat melting plastic (resistance in the connection) which led to the wiggling contact behavior addition; could relate to wimpy docking procedures -- better safe than melting. Who knows what improvements might come in the next release? They don't describe them all, not unusual.
It works well enough for my purposes. Excellent work all in all, with so many aspects, despite still a work in progress.