Currently if a story has belonged to more than one sprint, the sprint field concatenates the sprint.
For example, a story was in sprint 2019.5 and then moved to 2019.16 and then moved to unscheduled. In JIRA the story is none +2 indicating that it is currently not scheduled, but was twice previously. In Aha!, the custom field is 2019.15, 2019.16 - that is not both tags, that is a new tag created. This elongates the list of values for sprints and makes it unusable for reporting.
The sprint field in JIRA does not allow commas, so it would be great if you could read the comma and understand that there is more than one value or if JIRA allows you to see the current sprint in the API and not the past.