This may have happenedĀ because their email provider is flagging them as junk mail since Planning Center is sending the email on your behalf. Because providers change their definition of what they think is junk quite often, this can happen at any time, even if you were getting these emails successfully in the past.
To tell their email provider to stop blocking Planning Center emails, they’ll need to whitelist them by adding ‘no-reply@planningcenteronline.com‘ to your address book. More info on whitelisting, including specific instructions for many popular email providers, can be found at the following link: Email Whitelist Instructions.