The first thing to do here is to make sure the sensors are clean and free of spider webs, dust or anything else that they might confuse with a parking obstacle. If that doesn’t stop them false-alarming, I’d be letting a Hyundai specialist take a look, as it doesn’t sound like something that can be fixed in the driveway at home. Perhaps you’ll need to replace one or more of the actual sensor units.
But there’s one other possibility that, although it’s a bit of a long shot, might explain what’s going on. Does the problem occur when you’re in traffic and another car ranges up behind at the lights? If so, is the car behind you likely to be one with active cruise-control. If it is, you might find that the radar signal for the other car’s cruise control is actually triggering your parking sensors. I’ve heard of it happening.