You are able to connect to your smart trainer, but once you start and ride you do not feel any resistance changes as the slope changes.

Please make sure there are no applications (such as Garmin or Zwift) that are using the ANT+ service running in the background. If there are please close them and restart RGT.
Please make sure that you close all applications on your mobile device or tablet that are connected via Bluetooth to the trainer as well and then re-start RGT.

How to kill a process on MacOS:

How to kill a process on Windows:

Most of the times by cycling the power on the trainer Off/On, the resistance will return. Deselect your trainer from the Trainer tab, cycle the power on trainer, once it's back On select your trainer again from the Trainer tab.  

If you are still experiencing issues, please press the 'S' key in RGT and submit a ticket from within so we can capture the logs to investigate what happened.