We have released an update to the Isaac ROS CLI to ensure it downloads the correct image.
Please try this:
sudo apt-get update && sudo apt install isaac-ros-cli
Confirm the new version of the CLI package shows up as 1.0.1:
apt-cache policy isaac-ros-cli | grep Installed
Finally, rerun the activate command:
isaac-ros activate
If you still run into any other issues, please let me know. Thanks.