Whilst checking the list of my subscriptions, I gave it another go and I noticed the below:

When first landing on the Subscriptions page, one can use the cog wheel to the right of each line, to open Self serve portal and get to download the invoices

However, on second attempt, the Self-serve portal opens for the same subscription, irrespective of which line I click.

After a page refresh, I can access another item, and if I want to get all invoices, all I have to do is refresh the page every time.

I now have all my invoices, can you confirm if this behavior for the Self serve portal is by design or a glitch?