Using MacWorld App on iPhone

I was using the MacWorld Digital App on my iPad mini with a 12 month subscription that I began in January. I have since traded in the iPad mini and am wanting to continue reading MacWorld on my iPhone. When I go into the app to open a magazine, it has the subscribe option. If I click on this and the following subscribe options, it eventually tells me I'm currently subscribed and then I click Ok. But then it never takes me into the magazine, it just has the magazine cover and below looks like it's loading something but no read option ever appears. Any ideas?

Thanks,

Dan