Marketing Cloud Next - Preference Page and Subscription in Consent tab

Please check if the right domain name is is in the allow list or not 

1. Open the following link: https://DOMAIN_NAME.lightning.force.com/lightning/n/standard-PrivacyPreferenceCenter

2. Under both the Default Email Preference Form and the Default SMS Preference Form, click the dropdown menu and select 'Configure Allowed Domains.'

3. Remove all currently configured allowed domains and click Save.

4. Click the dropdown arrow again and select 'Add Domain.' Enter the domain: https://DOMAIN_NAME.my.salesforce.com and click Save.

5. Once done, open this link to check if you're able to preview the Preference Manager: https://DOMAIN_NAME.lightning.force.com/lightning/n/standard-Consent