The run you are attempting to access is already complete and will not accept new groups.
The existing run is: https://dashboard.cypress.io/project/abcd/runs/1
When a run finishes all of its groups, it waits for a configurable set of time before finally completing. You must add more groups during that time period.
The --group flag you passed was: foo
The --parallel flag you passed was: true
https://on.cypress.io/already-complete