At a small local competition this season, I saw a match where a competitor’s robot kept moving after the other robots were disabled (note - the team moving was clearly as surprised as anyone else!). I’m pretty sure the robot was using Cortex, and from an outside observers point-of-view it appeared that everything was attached correctly by all robots on the field. This was after several other technical issues with the same match on the same field and the determination (as far as I’m aware) was field-fault (very low-stakes - an early qual match).
That same field cause endless problems throughout the day for many teams (in fact it was so bad that my team brought it up with the EP and requested that the field be double checked & possibly taken out of play for finals after we had 2 separate qual matches on it with disconnect issues on the same tower same spot). We spent some time discussing it with other people present (competitors, mentors, EP, etc) and, while nothing was ever truly resolved, I personally was leaning towards it being a faulty field cable.