In my experience, 'Current Balance' simply refers to the finalised amount for the previous month, which appears several days after the calendar month ends, and remains there until you get the email that 'We've transferred your earnings to Stripe', when the heading again disappears from the side bar.

I don't know if this is what you are seeing, or if it functions the same in all countries, which may have different time lags for the two-step process from medium to Stripe to us.

But I don't see anything of that nature on my MPP page, having received the Medium funds transfer email 2 days ago.