Unable to access next video/unit of WP development course

Heading says it all really.

Just enrolled on the WP development beginners course and have watched the opening video - there doesn't appear to be anything else I need to do in order to move forward.

Problem is that it doesn't recognise that I've watched that video and show me the next video/unit.

I'm still in the trial period - that's my only guess as to why?

Thanks for your help.