If I switch to gr() backend, the code runs without problems.
The same happens if I run another notebook.
The problem appears to have started a few days ago when I updated the Julia packages, where amongst others pyplot() had to be installed via Conda.add(), etc.
The reason why I still prefer to use pyplot() over gr() is that:
gr() still has weak spots wrt. rendering text with LaTeX symbols.
gr() sometimes gives “ugly” results, e.g., the following when plotting the result of a Turing model fit:
[GR incorrectly doesn’t show the ylabel in the left column, and the label in the right column (“Density)” is written into the area of the left column.]
Not familiar with Turing.jl but it seems that some Plots recipe is missing/broken.
Have you tried using StatsPlots to see if an appropriate recipe is triggered?