My sort of interesting experience:

I tried to buy the LE on the launch day, and couldn’t get through the payment page. When it was listed as sold out, I bought a regular deck without much difficulty.

Then I saw the LE was available again, and decided to try to buy it again. I was planning to cancel my original order if I could get the LE.

I tried to check out dozens of times, but on the final page I kept getting the “something went wrong” error.

Finally, I decided to cancel my original order (you can do this by requesting a refund on the order page). The refund was issued 15 minutes later.

I went back and tried to order the LE again. Went though on the very first try, post refund.

So from my limited experience, I think Steam might be blocking all LE orders (and maybe even regular deck orders?) if you already have an active order.