Thanks David. This was indeed the prefix. After correcting it, I could navigate through the files backed up from the other Mac.

Hi , thanks for your response.
This is exactly the setting I planned to use. However, I've decided to move to the S3 one zone IA storage tier because keeping versions for 6 months, with a weekly or daily backup, would consume a lot of storage space.

Anyway, thanks for your support.

Here is the response from the support and I can confirm that their action plan resolved my issue:

Hello Nicolas,

Thank you for contacting us.

It is not a bug. The backup is performed according to the local database, containing all the records of the files uploaded. It was not updated, which resulted in this behavior.

Please synchronize the repository following these steps:
1. Go to Settings - Application - Synchronize Repository.
2. Choose your account from drop-down menu.
3. Press Synchronize Now

Please let us know if it helps.

Thank you

I will do that. Thanks for your help.

No, I did not only change the storage class. I deleted the existing plan, then created a new one with even a different name.