When attaching atom to the existing environment that has password type environment extensions configured, e.g. database connection, FTP connection, the processes deployed on the newly attached atom start failing with connection errors, however processes deployed on the "old" atoms work fine.
This is expected behavior. If you attach a new atom to the environment, you must re-enter and save all password type connection extensions. See Process extension values.
After attaching the atom to the environment, you will need to re-enter the password for all connection extensions within environment extensions and save the changes. You do not need to redeploy all the processes. The saved values should take affect with subsequent executions.