ERG mode works, but SIM mode does not

Hello. I recently bought a Tunturi e60 exercise bike and I have been using it with zwift. In the workout section it works fine, and the erg mode changes resistance as it should. However when I go for a free ride, zwift doesnt automatically change the resistance according to the elevation change. This is quite annoying as I have to change the resistance manually to have any chance to move forward in uphill terrain. Is there a setting I need to change, is my bike somehow not supported for SIM but is supported for ERG or is it a bug?