In the German forum
they also stated that they changed the approach to linking readers to the PB cloud.
If you buy a reader in a shop, it will be automatically linked to that shop. If you buy the reader from somewhere else, it will not be linked to any shop. Without a link to a shop, you don't have access to the cloud (with your e-reader).
The solution is to select a bookshop in the pocketbook cloud web interface, copy their URL, and send an e-mail with that URL and your e-reader serial number to the Pocketbook support asking to link the two.
They will add an entry in their DB and after a factory reset, the cloud should work on your e-reader.
Really not that simple and took me some time to find that information on page 20 of some forum post (they are a plague!)