All items that were exclusively assigned to a top-category could be ordered normally before the update, only after the update they were still assigned, but no longer orderable.
Overall, the problem seems to be expanding, because not only the categories are a problem, but also the link assignment (as can be seen in other posts here)
Michael Telgmann has already published something about this in the Shopware Issuetracker.
I think there is an urgent need for action here, because if people come back from Easter holiday and run updates without being informed about the errors, they will destroy their entire shops.