Quick Tip #2: If you can't access the B.O.S Shop

[placid tundra]

You need to retrigger the quest by revisiting Earth 10. The chest in there should be closed - open it again, get your reward.

Hop back to your house, open the mail for the same 'kill 30 monsters' task.

The counter only starts once you retrieve the mail.

[ebon crystal]

Bumping this because I was really confused! Thank you