Holoview hover is behaving differently than bokeh HoverTool

I noticed a difference in HoverTool display when I use the default holoviews option of “hover” vs providing Bokeh HoverTool explicitly.

In this first section, I used bokeh HoverTool to create hover

from bokeh.models import HoverTool, CustomJSHover
import holoviews as hv
import numpy as np

df = pd.DataFrame(
    {
        "zero": [0, 0, 0, 0, 0, 0, 0],
        "one": [1, 1, 1, 1, 1, 1, 1],
        "two": [2, 2, 2, 2, 2, 2, 2],
    }
)

hover = HoverTool(tooltips=[("x", "$x"), ("y", "$y")])

img = hv.Image((df.index, np.arange(df.shape[1]), df.T)).opts(tools=[hover])
rasterize(img)

The rasterized image doesnt display anything while hovering the plot

enter image description here

In this second section, I used the "hover" option available in holoviews.

from bokeh.models import HoverTool, CustomJSHover
import holoviews as hv

df = pd.DataFrame(
    {
        "zero": [0, 0, 0, 0, 0, 0, 0],
        "one": [1, 1, 1, 1, 1, 1, 1],
        "two": [2, 2, 2, 2, 2, 2, 2],
    }
)

img = hv.Image((df.index, np.arange(df.shape[1]), df.T)).opts(tools=["hover"])
rasterize(img)

With second option, I can see the HoverTool working fine

How can I make sure, I get the z option while using bokeh HoverTool to create hover

Thanks