I have a holomap created with a stack of rasterized Points. The direct plotted holomap is dynamically rasterized while the layout of it isn’t.

Here is a minimum example:

```
import numpy as np
import pandas as pd
import holoviews as hv
hv.extension('bokeh')
import holoviews.operation.datashader as hd
import datashader as ds
lon = np.array([8.75,8.76,8.77])
lat = np.array([46.1,46.2,46.3])
index = np.array([0,1,2])
dates = np.arange(4)
temp = np.random.random((4,3))
point_stack = {date: hv.Points(pd.DataFrame({'lon':lon,'lat':lat,'temp':temp[i,:]}), kdims=['lon','lat'], vdims=['temp']) for i, date in enumerate(dates)}
hmap = hv.HoloMap(point_stack, kdims='Dates')
hmap = hd.dynspread(hd.rasterize(hmap, aggregator=ds.first('temp'),vdim_prefix=''))
hmap # it plot perfectly
hmap.layout() # it loses the dynamics
```

The result of the failed one after zoom in looks like:

I am using

```
holoviews 1.18.0
datashader 0.15.2
```