Broken dynamic eq_hist Bokeh Datashader plots with colorbars

At first I thought this was a Bokeh issue, but I haven’t been able to reproduce it in a static export or by following Bokeh examples, so I’m filing it here on HoloViews. Specifically, a Datashader plot with eq_hist and colorbars works fine if it’s not dynamic:

import dask.dataframe as dd, holoviews as hv
from holoviews.operation.datashader import rasterize, dynspread
import bokeh, datashader as ds
hv.extension("bokeh")

df = dd.read_parquet('data/nyc_taxi_wide.parq').compute()
pts = hv.Points(df, ['dropoff_x', 'dropoff_y'])
opts = hv.opts.Image(cnorm='eq_hist', colorbar=True, width=700)
ds.__version__, hv.__version__, bokeh.__version__

but it fails if dynamic=True:

Here the immediate symptom is that the colorbar labels are gone, but more seriously as soon as the user pans or drags, the plot flickers briefly into a massively zoomed in bit of the plot, roughly like:

then disappears altogether:

After the plot disappears, the JS console shows:

It works fine if there is no colorbar or if cnorm='log', so it seems like it’s something to do with showing an eq_hist colorbar dynamically. I see the same behavior with bokeh 2.3.0, 2.3.1, and 2.3.2.

[mattpap]

I will submit a PR and target this for 2.3.3 together with layout regression fixes.

[philippjfr]

@mattpap Here’s the notebook I promised https://anaconda.org/philippjfr/broken_colorbar_labels/notebook

Click the button and you’ll be able to reproduce the error and hopefully debug it.