Whenever we attempt to register a participant through an offline registration, we cannot select a specific participation type. The event is accepting registrations and there are no limits on registrations for that participation type.
You will want to check if the participation type is configured for Delayed Self-Pledge. Delayed Self-Pledge participation types can only be selected during a front-end registration. This is to ensure that the appropriate information and consent is gathered for any possible charges due to not meeting the fundraising commitment.