Same for me.
If I click on Log In from the shop, I can enter my email and password with no problem. If I then select ‘My Account’ I just go back to the login page and get into the same endless loop.
This is on Internet Explorer from my PC as well as Safari on my Ipad.
This is a problem as I am trying to see if a dispute I had has been resolved.
I can click on ‘My Wishlist’ and am taken to it (this is, correctly, shown as empty). Clicking on ‘My Subscriptions’ after that, takes me to my subscriptions page. This page shows as empty and does not show my PC membership.
I have just managed to log in. This could have been a fluke but I logged out and then selected ‘My Account’. This time it accepted my log in.
Could be worth a try.