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.
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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 already exist on the N2K bus. If N2K already has these values, 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 can send it with your tracking data.

DataHub AI polars don't need to have TWS and TWD;. They will use the extra info if it's there, but it's not essential. AI Polars need lat, long, SOG, COG, AWS, and AWA. Ideally, they should speed through water, but if not, they can estimate this through SOG, COG, and current models.

With Raymarine Axiom 9 and other MFDs, the primary MFD's data source needs to be set to the EV-1 Course computer, and True Heading HTD instead of magnetic should be used.
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This will allow the HDT to be sent to the DataHub on the N2K feed. Then it can generate TWS and TWD.

The heading data source can be selected in the Axiom by:

True or Magnetic can be selected either from the Axion in Settings > Units (to the left of the Network tab) or from the P70 control head Menu > Set-up > User Preferences > Units.