I think I have seen this as well. Radar is an imperfect technology. There are many types conditions that cause the radar to produce anomalies that the software cannot properly interpret. The manual for the 2018 Honda Accord lists several conditions that limit the sensing system's performance (p.512).
Environmental conditions
- Driving in bad weather (rain, fog, snow, etc.).
- Sudden changes between light and dark, such as an entrance or exit
- There is little contrast between objects and the background.
- Driving into low sunlight (e.g., at dawn or dusk).
- Strong light is reflected onto the roadway.
- Driving in the shadows of trees, buildings, etc.
- Roadway objects or structures are misinterpreted as vehicles and pedestrians
- Reflections on the interior of the windshield.
- Driving at night or in a dark condition such as a tunnel.
Roadway conditions
- Driving on a snowy or wet roadway (obscured lane marking, vehicle reflected lights, road spray, high contrast).
- Driving on curvy, winding, or undulating roads.
- The road is hilly or the vehicle is approaching the crest of a hill.