you for reaching out on the community and telling us about your issue. I do apologize for the issue you're having. I'm wondering here if the column may not be enabled. To double check we can go check by selecting the register. In the bottom right select column and you should see a list of options and you'll want to make sure the balance option is highlighted blue. There's also quite a few other options that you can explore but that should bring your running balance back up ideally.
let us know if this helps resolve the issue for you.