I wonder if it is completely necessary to set the data conectivity mode to Direct Query when you want it to set the incremental update option. I had set it to Import the first time and I don´t know if it will be a requisite.
You haven't outlined your use case. For most Incremental loads, it will be for importing data only, so use Import Mode. You can set it to incrementally load as well as direct query, but it isn't required, and is only required/requisite for combining real-time datasets and imported refreshes.