Surface Slope Label Style - "Fixed Length Broken?

I am attempting to modify my surface slope label style so that the slope arrow is a fixed, user-defined length rather than automatically connecting the two elevation points. Although the Fixed length option is available, enabling it has no effect—regardless of the value entered (e.g., 1 m, 0.0001 m, or 10 000 m), the arrow continues to stretch between the two slope points.

Additionally, the Anchored to setting for the arrow component is locked to <Feature>, and I am unable to change it to <Surface slope>; the option appears but cannot be selected.

Any guidance on how to configure the label so that the arrow uses a fixed length rather than spanning the entire slope feature would be greatly appreciated.

Thank you.