ERG mode doesn't seem to work

Recently bought an Elite Zumo and have noticed recently that ERG mode doesn’t seem to work - i’m spinning at the same level regardless of incline in zwift. I’m connected via bluetooth to a mac. Anyone nwo fo a fix for this?

@Justin_Hutton-Penman that is how ERG mode is supposed to work. The two types of training control for Zwift are:
SIM: resistance changes based on the grade you are currently riding, ie riding up an 8% grade will feel harder than a 0% grade

ERG: Zwift sets your trainer to a specific watt output and no matter what you do your trainer will maintain that wattage. This is for training where you want to hold a certain amount of watts for a set period of time.

I see. I thought it was the other way around. Thanks