Of course the Niro can charge the battery using ICE, your flow diagram will show that. The question is more about if the software PHEV partition of some of the SOC can be overridden in some circumstances. We seem to have some credible reports both ways. Not knowing the exact methodology and not owning a PHEV myself to test, I'm not sure what is going on here. We also have a number of reports of HEV owners who report charging the battery unusually high by running in Sport. I almost never use Sport, but in my experiment to determine the true gas tank capacity, I did run in Sport for about 20 miles trying to run out of gas faster, and indeed my battery charge went up to three quarters or so, a seldom seen charge for me.
It doesn't really matter one way or the other as running Sport to charge the battery is clearly inefficient to say the least. But it is still interesting. Got to wonder about the conflicting reports.
2018 Kia LX HEV Metal Stream with Advanced Tech