[2021] Give me my money back!

Just restart the Steam client a couple of times, the DLC will “relink” correctly and your items will eventually reappear.

If you’d still like to proceed with a refund, let me know and I can sort that out for you.

It is bizarre for this issue to persist as long as it has, I presume all DLC are enabled in the Steam library? As for the refund, please add me on Steam and PM me so I can verify that the Steam account belongs to you.