All documents are classified as unknown after upgrading to 18.104.22.168 for batches sent through an encrypted batch class. This only effects encrypted batch classes that were already imported to a 22.214.171.124 system which is then upgraded to 126.96.36.199.
Between release 188.8.131.52 and 184.108.40.206, there was a change to the encryption schema for encrypted batch classes. When upgrading from 220.127.116.11 to 18.104.22.168, if the batch class was encrypted before the upgrade, all batch instances will have documents classified as unknown document types.
The solution to this is after you upgrade from 22.214.171.124 to 126.96.36.199, you will need to ‘learn files’ in the encrypted batch class before sending any batch instances though the encrypted batch class.