I'm accessing my JDV table via OData4 through Salesforce's UI builder. The salesforce engine itself is creating the OData calls, and whenever a $filter is needed with multiple columns, it looks like salesforce pads the column name with a space in front and behind. That'll make the URL look like ...$filter=%20ColumnA%20eq%20123%20and%20ColumnB%20eq...
The first space right after the $filter= throws off the JDV engine as it thinks it's a malformed URL - which I guess it is. The thing is when I tested it via the OData2 interface, it accepted it just fine. I'm not sure if the OData4 specifications explicitly state in terms of the URL, so it could be anybody's bug. Perhaps we could make JDV a little more forgiving and trim the spaces after un-URL-encoding the URI.