I am using a Tacx Vortex and the resistance is not altering.
I have updated the firmware, and calibrated the trainer.
I have paired the trainer.
Yet when I get to a hill, the resistance does not change.
I have tried this on 2 computers with 2 different ant+ dongles.
I have connected the trainer to Bcool and the resistance changed instantly.
             
            
              
              
              
            
            
           
          
            
            
              try disconnecting your Vortex in the Tacx app before using it in Zwift. It is a known issue. 
             
            
              
              
              
            
            
           
          
            
            
              Done that…  Switched Bluetooth off as well.
 
Thanks
             
            
              
              
              
            
            
           
          
            
              
                EricC
                (Eric )
              
              
                  
                  
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              Hi Mark,
Make sure trainer difficulty is set to beyond zero and that it is paired as both a Power Source and a Controllable Trainer.
             
            
              
              
              
            
            
           
          
            
            
              Difficulty needs putting to 100% in settings
             
            
              
              
              
            
            
           
          
            
            
              It was the ant+ stick. Bought a new one, seems to have been solved.