This bug is due to a change we made with Megaphones and then had to revert, so sometimes you will have this come up (usually only once).

To fix this bug, do the following in order:
  1. Make sure your client is up to date with the launcher
  2. Sort your marketplace bag
  3. Delete any existing megaphones
  4. Sort your marketplace bag
  5. Double check that there are no blank spaces with missing icons; drag to delete these, or use the bulk delete option
    1. If you have not updated your game via the launcher, you could potentially delete new items
  6. Sort your marketplace bag
  7. Purchase new megaphones
The process is a little over the top, but it does guarantee that you'll fix the error.