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