I drag issues into the sprint section at the top of a backlog and when I click on Start sprint, it will tell me that only 1 issue will be in the sprint or even 0 in some cases. I only have this issue with one Jira company-managed Scrum project.
As you can see in my screenshot, I have 4 issues loaded but it says "1 issue will be included in this sprint"

I anticipate that part of the problem here is that the Jira Issue(s) was associated with a prior sprint in which it remained in the to-do or in progress, and when asked to carry over to the next sprint I clicked yes (most likely). When I click into the Issue now, I see that it is not part of any sprint but was in another sprint, which I think is getting in the way for some reason.
Lastly, I get the same problem in this project for both a currently running sprint or a new one being planned that has not started.
Any ideas? If necessary, how can I possibly remove the previous sprint association from these Jira Issues?
Thanks, Ronny