What worked for me:

1. Sign in to wallet.hive.blog using your Memo key. It may help to open it in a private browsing/incognito tab for this purpose.
2. When you send your HIVE with the message as shown in the post instructions above, it should ask you to confirm the transfer with your Active key, but the Memo key should have already assigned encryption as described above.
3. You can then verify successful encryption by going to your account view in hiveblocks.com to see what the public can read.