Short answer: There are 256 element – 64 per class.
Longer answer: There are NOT unique 256 element labels. The English language is not precise enough to distinguish the difference between Pursue in the context of the Activity class, versus Pursue in the context of the Fixed Attitude, Situation, and Psychology classes. Therefore, we used the reduced (chess) set of 64 labels and let context imply the subtle differences.
Here is an explanation pulled from the middle of an FAQ on Dramatica.com:
The different patterns within each class are understandable when you look at how the Dramatica structural model is built. The bottom level is where the elements from which you build your Overall Story characters are found. Unlike the top three levels, however, each item does NOT have its own unique label (e.g. Pursuit and Consider). There is one set (or what we call a “chess set”) of 64 unique labels which cover all of the elements for a single Domain/Throughline. Dramatica consists of four Domains and the elements appear within each of these Domains. The DIFFERENCE between the elements of one Domain and another is the arrangement of the elements within the quads. Though a dynamic pair is never split (e.g. Pursuit and Avoidance), it will be paired with different dynamic pairs to make up each quad. The combination of the four elements within each quad is different from domain to domain. These combinations create slightly different contextual “flavors” for the elements which substitute for unique labels. Therefore, Pursuit in a Situation domain is subtly different than Pursuit in an Activity domain because of the shared elements of the quad in which it is found.
Source: How do the character elements work in each of the throughlines? - Questions - Dramatica