create_ramp_legend only show legend partially when max value is high

I am producing a property value (up to $22,900,000) map and I want to add a ramp legend based on the values. However, the ramp legend always showed up partially, meaning only the colors corresponding to the lower values were rendered but not those for higher values.

I noticed in bokeh_ext.py, line 410:

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legend_fig.image_rgba(image=[img.values],
x=[min_val],
y=[0],
dw=[max_val - min_val],
dh=[18],
dw_units='screen')

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"dw" is supposed to be the width of the legend? not the value range, right? Anyway, if I set it to an arbitrary value such as 900, I can get the full legend.

Let me know if I am looking at the right place or something I am missing in my understanding.

Thanks.