The Recovery Manager Portal relies on unpacked backups to restore from. It is likely that either no backups are unpacked in the event that no dates are listed, or the backup from the required date is unpacked.
It is also possible that the collections are configured to be encrypted with a password. If backups are encrypted, they are not automatically unpacked. For this reason, there are no unpacked backups for the Portal to use. Enhancement ID RMADFE-1351 has been submitted to the product team to add a feature in the portal to supply a password for encrypted backups.
Ensure the backup collections in the Recovery Manager console are configured to create unpacked backups. This can be configured on the properties of the collection under the "Unpacked Backups" tab. The portal also looks at one specific DC for its unpacked backups, so it is possible that the specified DC has no unpacked backups as well. This DC can be found in the Portal under the Configuration page and within each domain in "Active Directory Domains". It is best practice to have one collection with just this DC, configured with as many unpacked backups as needed to restore from.