When you do a bulk operation to add subscribers to a sequence, they won't be added to the automation. Only people who complete the entry point (submit the form, landing page, or get a tag) at the top of the automation after the automation was activated will be added to the automation. So even though they will be in the sequence from the bulk operation, they won't get anything else in the automation.
You can add existing subscribers to the automation by using a temporary tag. Here are some steps
- At the top of the automation, add the tag as the event (Is added to a tag) option
- In bulk operations, go to the list of people that you want to add and use the Add a Tag option. Give them the tag you used in the automation above