Kickr and Zwift working

I’ve read multiple posts about Kickr problems.  So, here’s one about it working.  I’ve been using TrainerRoad for several months.  In fact used it yesterday morning (erg mode).  I then started the kickr app on my iphone, changed the setting to sim (I left the app running as if I was doing a workout) and then started up Zwift.  Had no problems throughout my ride.  Resistance changed according to the grade and my pace.  Completed a one hour ride this morning with no problems with the  identical process.

Vernon if I understand well what you say, for the Zwift to control the resistance on the Kickr I need to have the Kickr (Wahoo) app on my phone running in Sim?

Right now the I’m using the app on Level 3 and the Zwift basically recognizes the Kickr as a powermeter and it does not control the resistance.

Thanks in advance for your any input you can provide.