I had the same problem....All you have to do though is add any game into your cart, then you can login that way. ;)
EDIT: You don't have to buy said carted game...but, you probably really should ;p (joking!)

On the main page, the recommended tab lists many games I already own. I actually already own half of the games it recommends to me. Some of those games also show up on the Bestsellers and New releases tabs, but they're greyed out there. I think it would be better to only recommend games I don't own yet or at least grey them out like on the other tabs.

The bug occurs again for me. This time it is an empty slot between Messiah and Freedom Force vs. the 3rd Reich.

You mean the bug was fixed and then appeared again? I didn't think it was ever fixed.

No it was not officially fixed, but it was sort of *fixed* for me by re-ordering the shelf back then. This time, however, it does not solve it.

It seems that manually typing quotes doesn't inform the quotee of the reply. I seem to remember a blue telling us this should work.

SirPrimalform and maxman43 noticed it here.

Another one:
When clicking the "private message" flag, then dismissing the list of users that appears without going to the PM page, the "forum reply" flag appears as well, showing 0 replies.

Edit: picture added

This did post triggered the notification ?

Nope

Addition: this seems to affect all flags, when displaying and dismissing the "my cart" list, both the "messages" and "forum replies" flags are displayed, see attached image.

So what happens if you empty your cart?

If I reload the page, the "0" flags are hidden again, if no flags are visible, I can't get them to display (because they're only displayed once I show and dismiss the list for the messages/cart - that is, the list that's displayed when clicking the flag, not the page displayed when clicking "check out now" or the name of whoever sent me a message).

If the cart is empty, I have no messages, and no replies: Nothing is displayed.
If the cart is empty, I have at least one new message, but no replies: at page load, the "my message" flag is shown, after showing and dismissing the list, "my messages" and "forum replies" are shown.
If I have something in the cart: at load the "my cart" flag is shown (as well as any other flags with a count above 0), when showing and dismissing the cart list, all flags are shown (including 0-count).

Removing all items in the cart (through the list) only removes the cart flag, the other flags are still there (even 0-count).

That is odd, because there was a similar bug before they apparently rewrote all the code at the so called end of beta. Although of course there was no messages back then and the reply notification would not go away no matter what you had (or didn't have) in your cart.

I believe that was because the reply count was not updated when a thread was deleted (you couldn't open the thread to flag that post as read). That was (temporarily) solved by having staff update the unread count to 0, and I suppose the back-end code was updated to prevent it from happening again.

This bug regards the displaying of the flag, not an erroneous count.

Thanks.