Running on MacOS 11.2 (Big Sur). I have both the AWS CLI and session-manager-plugin installed, and if I try running session-manager-plugin directly from a VSCode Terminal I see this:
% session-manager-plugin
The Session Manager plugin was installed successfully. Use the AWS CLI to start a session.
When I start a new CloudSession it says connected, but then when I try and click on it this message appears in the bottom right corner.