Same problem on 2 separate WordPress sites.
At first I had trouble with audio in a video. The video used to play but without any sound:
Now neither visuals or audio appear. Client might have changed something.
However, here are a few test I made with different plugins:
This is the original files:
I initially installed a plugin at a time, deleting each as I went to avoid conflicting scripts, but as results were always the same, I decided to install them again for the sake of this post.
Hope someone can help.
Many thanks in advance,