The reason there is no TWS and TWD data in the N2K feed is almost always because there is no HDT in your N2K feed.
The hub will compute TWS and TWD if AWS, AWA, COG, SOG, and HDT are defined in the N2K feed.
This is done ONLY if TWS and TWD do not exist on the N2K bus already. So if N2K already has these values, then the HUB will not compute them since they already exist.
If you only see AWA and AWS when the boat is still, it often happens that when you are moving and the chart plotter is on, it uses the GPS in the chart plotter to generate COG, SOG and HDT. At that point, the DataHub can generate TWS and TWD, or your chartplotter can calculate it.
You could test this by adding an instruments data box to the chartplotter screen with TWS and TWD, AWA, and AWS.
Then you may see it appear when sailing. Or if it is just shown in the DataHub NMEA > Navigation tab looking like this:
Then the DataHub generates it and is able to send it with your tracking data.