pixel_player86574295
Unfortunately, there were a lot of issues when releasing the new event, but your one is a new.
Please check it again: the all treasure pieces locations.
And if the searching is not succes, you have to contact Pixel Support.
https://portal.pixelfederation.com/en/diggysadventure/support
On your game screen, choose the Settings cog (Mobile, upper left corner; PC, upper right corner)
Send just one support ticket.
After you send the ticket you get the ticket number, take a screenshot or write that number, maybe you need it later.
And you have to wait for answer 2-3 workdays.