We're having the same issue for all of our apps. We used to be able to get through a full cycle of the monthly subscription in 30 minutes (6 renewals every 5 minutes). Now if it's going to take 1 day for the renewal that means it will take 6 days to test a full monthly subscription which slows down the testing process significantly.
To make matters worse is we can't manage our subscriptions within sandbox settings to cancel and expedite the process a little. We get a "cannot connect" error which is a whole separate issue. Apple please help!!