Where is Plex getting its actor thumbnails from?

With the new Web interface launched showing cast photos its become more obvious than ever that images for some top name stars are somehow missing.

Example: Drew Barrymore. Her actor thumb exists in both TVDB and TMDB but is missing in Plex. For her TV series Santa Clarita Diet, other people in the series have thumb images but not Drew.

For that series I get thumbnails for every actor but Liv Hewson
And according to the Devs, actor thumbs come from TMBd and or TVDB

Hmmm I wonder why I don’t? What would the trigger be? And oddly enough I DO get Live Hewson’s thumb on my system.

edit the preferences of Plex Movie under
Settings - Server - Agents - Movies - Plex Movie
set ‘Cast List Source’ to ‘TMDb’

Then refresh a movie (wait 1 - 2 minutes)

@OttoKerner thanks. I was aware of that setting and I do have it set that way but still lots of missing thumbs.

Update. Changing nothing but doing a refresh of that individual show has brought in all the thumbs. Wonder if Plex would have eventually done that itself??

@hstamas said:
Update. Changing nothing but doing a refresh of that individual show has brought in all the thumbs. Wonder if Plex would have eventually done that itself??

I just did the same thing and the picture for Liv showed up