If it’s like the Santa Fe it’s using TomTom live services for speed cameras. The camera locations are not built in to the loaded map, but are from an internet feed.
When on the drive I guess the car is picking up your home WiFi so it gets the camera feed. When you leave home you lose the internet from the home WiFi and the camera feed drops off.
The solution is to use your mobile phone as a personal hotspot (sometimes called tethering). The phone will broadcast it’s own WiFi network and use mobile 3G or 4G for the data. Most smart phones and networks support this and include it in the tarrif, but not all of them. For example, Essential Plans on 3 exclude personal hotspot, but all other 3 contracts include it. So first check with your phone network provider. Turn on personal hotspot on your phone, and then connect the Ioniq to that WiFi network.
Which version do you have? Hybrid/Plugin/EV. Just curious, am thinking about going down the EV or plug in route when we next change a car.