I've read some things in jira on the new functionality that was put into caching in the DIH but I wouldn't think it should break the old behavior. It doesn't look as though any errors are being thrown, it's just ignoring the caching part and opening a ton of connections. Also I cannot find any documentation on the new functionality that was added so I'm not sure what syntax is valid and what's not. Here is my entity that worked in 3.1 but no longer works in 3.6:
<entity name="Emails" query="SELECT * FROM Account.SolrUserSearchEmails WHERE '${dataimporter.request.clean}' != 'false' OR DateUpdated >= dateadd(ss, -30, '${dataimporter.last_index_time}')" processor="CachedSqlEntityProcessor" where="UserID=Users.UserID">