I have had the same problem for several issues, and eventually stopped attempting to read them on the iPad about 4 months ago.
I was able to successfully download the last two issues a couple days ago, as an experiment, but it took all night, and the battery was just about dead by the time it was done.
I'm not sure if it continues downloading after the iPad goes to sleep (or turns off), or if it's better to disable that function temporarily.
By the way, I appreciate the concise instructions Richard gave you for logging into Ask Alexander. They were just what I needed. Thanks, Richard.