The most common reason is that the trainer doesn’t support virtual shifting, either because it’s not supported, or needs a firmware update. Which trainer do you have?
Virtual shifting also requires that the trainer be paired via Bluetooth, so if an ANT+ dongle is present, remove it.
I looked at your server logs and your KICKR is using firmware version 4.3.0, which I believe means yours is a KICKR v5. which is not able to run the firmware required to support virtual shifting.