When I add instead: (clerk/html [:img {:src "notebooks/images/vegas.gif"}]) strange things happen. After clerk/show! I'm getting:

Clerk evaluated 'jar:file:/home/tsl/.m2/repository/io/github/nextjournal/clerk/0.15.957/clerk-0.15.957.jar!/nextjournal/clerk/index.clj' in 83.776813ms.

without clerk/html everything is rendered (no animated gifs though)

minimal notebook (inside fastmath project):

(ns simple
  (:require [nextjournal.clerk :as clerk]))


(clerk/image "notebooks/images/vegas.gif")

#_(clerk/html [:img {:src "notebooks/images/vegas.gif"}])