Jira Align does not allow users that do not have allocation to be assigned tasks during an ongoing sprint.
The separation is in place due to Sarbanes Oxley regulations (SOX for short) that say a business person or their named representative has to accept/sign off on technical requirements before they can be put in production systems. This is audited by external firms at any publically traded company and any privately held companies in a regulated industry annually.
In Agile, that means the product owner is the one who signs off on/accepts the stories and as such they cannot also be a developer in the team, otherwise they cannot prove separation of duties.
The compromise is to use the Analyst role. An analyst can do everything that a Scrum Master, product owner, or developer can do on a team, except:
- Terminate a sprint early
- Start a sprint (unless all team members are allowed to do so)
- Add a story to an active sprint (Team Coach role only)
Analysts can both own tasks and accept stories. This role should be used very sparingly on teams, but if you do not need to follow SOX regulations, you can use the Analyst role.