what, if any, cloud types are being observed at this station model?

Brief Explanations:

In a standard surface weather station model, cloud types are represented by specific symbols located above (high clouds), to the side of (middle clouds), and below (low clouds) the central circle. In the provided image, there are no symbols in the designated positions for high, middle, or low cloud types. The symbol to the left of the circle ($\infty$) represents haze, which is a lithometeor (present weather) rather than a cloud type. The central circle is $3/4$ shaded, indicating a sky cover of $75%$ (broken clouds), but the specific genus of the clouds is not indicated by any symbols.

Answer:

No specific cloud types are being observed at this station model.